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26,600
Rationalize the denominator of $\frac{7}{3+\sqrt{8}}$. The answer can be expressed as $\frac{P\sqrt{Q}+R}{S}$, where $P$, $Q$, $R$, and $S$ are integers, $S$ is positive, and $Q$ is not divisible by the square of any prime. If the greatest common divisor of $P$, $R$, and $S$ is 1, find $P+Q+R+S$.
23
2.34375
26,601
Given the taxi fare of $3.50 for the first 0.5 mile, and an additional charge of $0.30 for each 0.1 mile thereafter, and a $3 tip, calculate the total number of miles that can be ridden with a $15 budget.
3.333
0
26,602
What is the greatest prime factor of $15! + 18!$?
4897
0.78125
26,603
Determine the value of $x$ for which $(2010 + x)^2 = 4x^2$.
-670
10.9375
26,604
Between 1000 and 9999, the number of four-digit integers with distinct digits where the absolute difference between the first and last digit is 2.
840
1.5625
26,605
Six six-sided dice are rolled. We are told there are no four-of-a-kind, but there are two different pairs of dice showing the same numbers. These four dice (two pairs) are set aside, and the other two dice are re-rolled. What is the probability that after re-rolling these two dice, at least three of the six dice show the same value?
\frac{2}{3}
3.90625
26,606
Given the real numbers \( x \) and \( y \) satisfy the equations: \[ 2^x + 4x + 12 = \log_2{(y-1)^3} + 3y + 12 = 0 \] find the value of \( x + y \).
-2
1.5625
26,607
Given an arithmetic-geometric sequence $\{ a_{n} \}$ that satisfies $a\_1 + a\_3 = 10$, $a\_2 + a\_4 = 5$, find the maximum value of the product $a\_1 a\_2 \ldots a\_n$.
64
33.59375
26,608
The base of pyramid \( T ABCD \) is an isosceles trapezoid \( ABCD \) with the length of the shorter base \( BC \) equal to \( \sqrt{3} \). The ratio of the areas of the parts of the trapezoid \( ABCD \), divided by the median line, is \( 5:7 \). All the lateral faces of the pyramid \( T ABCD \) are inclined at an angle of \( 30^\circ \) with respect to the base. The plane \( AKN \), where points \( K \) and \( N \) are the midpoints of the edges \( TB \) and \( TC \) respectively, divides the pyramid into two parts. Find the volume of the larger part. **(16 points)**
0.875
0
26,609
When fitting a set of data with the model $y=ce^{kx}$, in order to find the regression equation, let $z=\ln y$ and transform it to get the linear equation $z=0.3x+4$. Then, the values of $c$ and $k$ are respectively \_\_\_\_\_\_ and \_\_\_\_\_\_.
0.3
35.9375
26,610
Let $c$ and $d$ be real numbers such that \[c^3 - 18c^2 + 25c - 75 = 0 \quad \text{and} \quad 9d^3 - 72d^2 - 345d + 3060 = 0.\]Compute $c + d.$
10
14.84375
26,611
Suppose there are $160$ pigeons and $n$ holes. The $1$ st pigeon flies to the $1$ st hole, the $2$ nd pigeon flies to the $4$ th hole, and so on, such that the $i$ th pigeon flies to the $(i^2\text{ mod }n)$ th hole, where $k\text{ mod }n$ is the remainder when $k$ is divided by $n$ . What is minimum $n$ such that there is at most one pigeon per hole? *Proposed by Christina Yao*
326
64.84375
26,612
Compute the integer $m > 3$ for which \[\log_{10} (m - 3)! + \log_{10} (m - 1)! + 3 = 2 \log_{10} m!.\]
10
4.6875
26,613
A geometric sequence of positive integers is formed for which the first term is 3 and the fifth term is 375. What is the sixth term of the sequence?
9375
24.21875
26,614
A truck delivered 4 bags of cement. They are stacked in the truck. A worker can carry one bag at a time either from the truck to the gate or from the gate to the shed. The worker can carry the bags in any order, each time taking the top bag, carrying it to the respective destination, and placing it on top of the existing stack (if there are already bags there). If given a choice to carry a bag from the truck or from the gate, the worker randomly chooses each option with a probability of 0.5. Eventually, all the bags end up in the shed. a) (7th grade level, 1 point). What is the probability that the bags end up in the shed in the reverse order compared to how they were placed in the truck? b) (7th grade level, 1 point). What is the probability that the bag that was second from the bottom in the truck ends up as the bottom bag in the shed?
\frac{1}{8}
6.25
26,615
A train arrives randomly sometime between 3:00 and 4:00 PM and waits for 15 minutes before leaving. If John arrives randomly between 3:15 and 4:15 PM, what is the probability that the train will still be there when John arrives?
\frac{3}{16}
1.5625
26,616
Four vertices of a cube are given as \(A=(1, 2, 3)\), \(B=(1, 8, 3)\), \(C=(5, 2, 3)\), and \(D=(5, 8, 3)\). Calculate the surface area of the cube.
96
11.71875
26,617
Find the least positive integer such that when its leftmost digit is deleted, the resulting integer is 1/19 of the original integer.
95
12.5
26,618
How many 12-digit positive integers have all digits either 1 or 2, and have numbers ending in 12, but have no two consecutive 1's?
89
7.03125
26,619
In quadrilateral $EFGH$, $m\angle F = 100^\circ, m\angle G = 140^\circ$, $EF=6, FG=5,$ and $GH=7$. Calculate the area of $EFGH$.
26.02
0.78125
26,620
In the diagram, \(PRTY\) and \(WRSU\) are squares. Point \(Q\) is on \(PR\) and point \(X\) is on \(TY\) so that \(PQXY\) is a rectangle. Also, point \(T\) is on \(SU\), point \(W\) is on \(QX\), and point \(V\) is the point of intersection of \(UW\) and \(TY\), as shown. If the area of rectangle \(PQXY\) is 30, the length of \(ST\) is closest to
5.5
0
26,621
Let $M=123456789101112\dots5253$ be the $96$-digit number that is formed by writing integers from $1$ to $53$ in order. What is the remainder when $M$ is divided by $55$?
53
10.9375
26,622
Find the smallest natural number ending with the digit 2, which doubles if this digit is moved to the beginning.
105263157894736842
92.1875
26,623
In the numbers from 100 to 999, calculate how many numbers have digits in strictly increasing or strictly decreasing order.
204
50
26,624
A cheesecake is shaped like a $3 \times 3 \times 3$ cube and is decorated such that only the top and three of the vertical faces are covered with icing. The cake is cut into $27$ smaller cubes, each $1 \times 1 \times 1$ inch. Calculate the number of the smaller cubes that will have icing on exactly two sides.
12
21.09375
26,625
Given a bag with 1 red ball and 2 black balls of the same size, two balls are randomly drawn. Let $\xi$ represent the number of red balls drawn. Calculate $E\xi$ and $D\xi$.
\frac{2}{9}
41.40625
26,626
In the quadratic equation $3x^{2}-6x-7=0$, the coefficient of the quadratic term is ____ and the constant term is ____.
-7
60.15625
26,627
Consider positive integers $n$ where $D(n)$ denotes the number of pairs of different adjacent digits in the binary (base two) representation of $n$. Determine the number of positive integers less than or equal to $50$ for which $D(n) = 3$.
11
0
26,628
In a sequence of triangles, each successive triangle has its small triangles numbering as square numbers (1, 4, 9,...). Each triangle's smallest sub-triangles are shaded according to a pascal triangle arrangement. What fraction of the eighth triangle in the sequence will be shaded if colors alternate in levels of the pascal triangle by double layers unshaded followed by double layers shaded, and this pattern starts from the first (smallest) sub-triangle? A) $\frac{1}{4}$ B) $\frac{1}{8}$ C) $\frac{1}{2}$ D) $\frac{3}{4}$ E) $\frac{1}{16}$
\frac{1}{4}
7.8125
26,629
Two boards, one 5 inches wide and the other 7 inches wide, are nailed together to form an X. The angle at which they cross is 45 degrees. If this structure is painted and the boards are later separated, what is the area of the unpainted region on the five-inch board? Assume the holes caused by the nails are negligible.
35\sqrt{2}
0
26,630
If a positive integer is equal to the sum of all its factors (including 1 but excluding the number itself), then this number is called a "perfect number". For example, 28 is a "perfect number" because $1 + 2 + 4 + 7 + 14 = 28$. If the sum of all factors of a positive integer (including 1 but excluding the number itself) is one less than the number, then this number is called an "almost perfect number". For example, 8 is an "almost perfect number" because $1 + 2 + 4 = 7$. The fifth "almost perfect number" in ascending order is     .
32
89.0625
26,631
Given an ellipse C: $$\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$$ (where $a>b>0$) that passes through the point $E(\sqrt 3, 1)$, with an eccentricity of $\frac{\sqrt{6}}{3}$, and O as the origin of the coordinate system. (Ⅰ) Find the equation of the ellipse C. (Ⅱ) If point P is a moving point on ellipse C, and the perpendicular bisector of AP, with A(3, 0), intersects the y-axis at point B, find the minimum value of |OB|.
\sqrt{6}
68.75
26,632
An organization initially consists of 10 leaders and a certain number of regular members. Each year, all leaders are replaced, and each regular member recruits two new members. After this, 10 new leaders are elected from outside the organization. Initially, there are 30 people in total in the organization. How many people will be in the organization after 10 years?
1180990
0
26,633
Six positive integers are written on the faces of a cube. Each vertex is labeled with the product of the three numbers on the faces adjacent to the vertex. If the sum of the numbers on the vertices is equal to $1386$, then what is the sum of the numbers written on the faces?
38
10.15625
26,634
In triangle \( \triangle ABC \), the lengths of sides opposite to angles A, B, C are denoted by a, b, c respectively. If \( c = \sqrt{3} \), \( b = 1 \), and \( B = 30^\circ \), (1) find angles A and C; (2) find the area of \( \triangle ABC \).
\frac{\sqrt{3}}{2}
42.96875
26,635
Given that $a$ and $b$ are positive numbers, and $a+b=1$, find the minimum value of $\frac{1}{2a} + \frac{1}{b}$.
\sqrt{2} + \frac{3}{2}
8.59375
26,636
Let $a$, $b$, and $c$ be the sides of a triangle with angles $\alpha$, $\beta$, and $\gamma$ opposite them respectively. Suppose $a^2 + b^2 = 9c^2$. Find the value of \[\frac{\tan \gamma}{\tan \alpha + \tan \beta}.\]
-1
0
26,637
The circumradius R of triangle △ABC is $\sqrt{3}$. The sides opposite to angles A, B, and C are a, b, c respectively, and it is given that $\frac{2\sin A-\sin C}{\sin B} = \frac{\cos C}{\cos B}$. (1) Find the angle B and the side length b. (2) Find the maximum value of the area $S_{\triangle ABC}$ and the values of a and c when this maximum area is achieved, and determine the shape of the triangle at that time.
\frac{9\sqrt{3}}{4}
12.5
26,638
Let point $P$ be a point on the ellipse $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 (a > b > 0)$. Let $F_1$ and $F_2$ respectively be the left and right foci of the ellipse, and let $I$ be the incenter of $\triangle PF_1F_2$. If $S_{\triangle IF_1P} + S_{\triangle IPF_2} = 2S_{\triangle IF_1F_2}$, determine the eccentricity of the ellipse.
\frac{1}{2}
57.03125
26,639
Simplify: $$\sqrt[3]{9112500}$$
209
21.09375
26,640
In a store, there are four types of nuts: hazelnuts, almonds, cashews, and pistachios. Stepan wants to buy 1 kilogram of nuts of one type and 1 kilogram of nuts of another type. He has calculated the cost of such a purchase depending on which two types of nuts he chooses. Five of Stepan's six possible purchases would cost 1900, 2070, 2110, 2330, and 2500 rubles. How many rubles is the cost of the sixth possible purchase?
2290
0.78125
26,641
Given a circle C that passes through points A(1, 4) and B(3, -2), and the distance from the center of the circle C to line AB is $\sqrt{10}$, find the equation of circle C.
20
0.78125
26,642
We randomly throw a 10-filér coin onto a $40 \times 40$ cm chessboard. What is the probability that the coin: a) will be entirely inside one square? b) will partially cover one and only one square edge? c) will partially cover two square edges but not a vertex? d) will cover a vertex? (The diameter of the 10-filér coin is $19 \mathrm{~mm}$).
0.1134
0
26,643
Let $n \in \mathbb{N}^*$, $a_n$ be the sum of the coefficients of the expanded form of $(x+4)^n - (x+1)^n$, $c=\frac{3}{4}t-2$, $t \in \mathbb{R}$, and $b_n = \left[\frac{a_1}{5}\right] + \left[\frac{2a_2}{5^2}\right] + ... + \left[\frac{na_n}{5^n}\right]$ (where $[x]$ represents the largest integer not greater than the real number $x$). Find the minimum value of $(n-t)^2 + (b_n + c)^2$.
\frac{4}{25}
0
26,644
Given the function $f(x)=\sin^2x+\sin x\cos x$, when $x=\theta$ the function $f(x)$ attains its minimum value, find the value of $\dfrac{\sin 2\theta+2\cos \theta}{\sin 2\theta -2\cos 2\theta}$.
-\dfrac{1}{3}
1.5625
26,645
Inside a square with side length 12, two congruent equilateral triangles are drawn such that each has one vertex touching two adjacent vertices of the square and they share one side. What is the side length of the largest square that can be inscribed in the space inside the square and outside of the triangles?
12 - 4\sqrt{3}
0
26,646
How many positive four-digit integers of the form $\_\_35$ are divisible by 35?
13
77.34375
26,647
Given the function $$f(x)=\cos\omega x\cdot \sin(\omega x- \frac {\pi}{3})+ \sqrt {3}\cos^{2}\omega x- \frac { \sqrt {3}}{4}(\omega>0,x\in\mathbb{R})$$, and the distance from a center of symmetry of the graph of $y=f(x)$ to the nearest axis of symmetry is $$\frac {\pi}{4}$$. (Ⅰ) Find the value of $\omega$ and the equation of the axis of symmetry for $f(x)$; (Ⅱ) In $\triangle ABC$, where the sides opposite angles $A$, $B$, and $C$ are $a$, $b$, and $c$ respectively. If $$f(A)= \frac { \sqrt {3}}{4}, \sin C= \frac {1}{3}, a= \sqrt {3}$$, find the value of $b$.
\frac {3+2 \sqrt {6}}{3}
0
26,648
A four-dimensional rectangular hyper-box has side lengths $W$, $X$, $Y$, and $Z$. It has "faces" (three-dimensional volumes) whose measures are $60$, $80$, $120$, $60$, $80$, $120$ cubic units. What is $W$ + $X$ + $Y$ + $Z$? **A)** 200 **B)** 250 **C)** 300 **D)** 318.5 **E)** 400
318.5
1.5625
26,649
In the sequence of positive integers \(1, 2, 3, \ldots\), all perfect squares are deleted. The 2003rd term of this new sequence is ____ .
2047
0
26,650
Trapezoid $EFGH$ has sides $EF=100$, $FG=55$, $GH=23$, and $HE=75$, with $EF$ parallel to $GH$. A circle with center $Q$ on $EF$ is drawn tangent to $FG$ and $HE$. Find the length of $EQ$ if it is expressed as a fraction $\frac{p}{q}$, where $p$ and $q$ are relatively prime integers.
\frac{750}{13}
0
26,651
Given a triangular pyramid where two of the three lateral faces are isosceles right triangles and the third face is an equilateral triangle with a side length of 1, calculate the volume of this triangular pyramid.
\frac{\sqrt{3}}{12}
1.5625
26,652
The integer $m$ is the largest positive multiple of $18$ such that every digit of $m$ is either $9$ or $0$. Compute $\frac{m}{18}$.
555
0
26,653
From the $8$ vertices of a cube, choose any $4$ vertices, the probability that these $4$ points lie in the same plane is ______.
\frac{6}{35}
25
26,654
A facility has 7 consecutive parking spaces, and there are 3 different models of cars to be parked. If it is required that among the remaining 4 parking spaces, exactly 3 are consecutive, then the number of different parking methods is \_\_\_\_\_\_.
72
0.78125
26,655
The calculator's keyboard has digits from 0 to 9 and symbols of two operations. Initially, the display shows the number 0. Any keys can be pressed. The calculator performs operations in the sequence of key presses. If an operation symbol is pressed several times in a row, the calculator will remember only the last press. The absent-minded Scientist pressed very many buttons in a random sequence. Find the approximate probability that the result of the resulting sequence of operations is an odd number.
1/3
0
26,656
Let $p$, $q$, and $r$ be the roots of the polynomial $x^3 - x - 1 = 0$. Find the value of $\frac{1}{p-2} + \frac{1}{q-2} + \frac{1}{r-2}$.
\frac{11}{7}
0
26,657
Find the sum $$\frac{3^1}{9^1 - 1} + \frac{3^2}{9^2 - 1} + \frac{3^3}{9^3 - 1} + \frac{3^4}{9^4 - 1} + \cdots.$$
\frac{1}{2}
25.78125
26,658
In the trapezoid \( ABCD \) with bases \( AD \) and \( BC \), the side \( AB \) is equal to 2. The angle bisector of \( \angle BAD \) intersects the line \( BC \) at point \( E \). A circle is inscribed in triangle \( ABE \), touching side \( AB \) at point \( M \) and side \( BE \) at point \( H \). Given that \( MH = 1 \), find the angle \( \angle BAD \).
120
5.46875
26,659
Let $M$ be a set consisting of $n$ points in the plane, satisfying: i) there exist $7$ points in $M$ which constitute the vertices of a convex heptagon; ii) if for any $5$ points in $M$ which constitute the vertices of a convex pentagon, then there is a point in $M$ which lies in the interior of the pentagon. Find the minimum value of $n$ . *Leng Gangsong*
11
5.46875
26,660
Given that point $P$ is a moving point on the parabola $x^{2}=2y$, and the focus is $F$. If the fixed point is $M(1,2)$, calculate the minimum value of $(|PM|+|PF|)$ when point $P$ moves on the parabola.
\frac{5}{2}
16.40625
26,661
For a pyramid S-ABCD, each vertex is colored with one color, and the two ends of the same edge are colored differently. If there are exactly 5 colors available, calculate the number of different coloring methods.
420
3.90625
26,662
Let's modify the problem slightly. Sara writes down four integers $a > b > c > d$ whose sum is $52$. The pairwise positive differences of these numbers are $2, 3, 5, 6, 8,$ and $11$. What is the sum of the possible values for $a$?
19
8.59375
26,663
Let $ABC$ be an equilateral triangle. Let $P$ and $S$ be points on $AB$ and $AC$ , respectively, and let $Q$ and $R$ be points on $BC$ such that $PQRS$ is a rectangle. If $PQ = \sqrt3 PS$ and the area of $PQRS$ is $28\sqrt3$ , what is the length of $PC$ ?
2\sqrt{7}
16.40625
26,664
Given the sequence $\{a_n\}$ with the sum of its first $n$ terms $S_n = 6n - n^2$, find the sum of the first $20$ terms of the sequence $\left\{ \frac{1}{a_na_{n+1}}\right\}$.
-\frac{4}{35}
1.5625
26,665
Write the process of using the Horner's algorithm to find the value of the function $\_(f)\_()=1+\_x+0.5x^2+0.16667x^3+0.04167x^4+0.00833x^5$ at $x=-0.2$.
0.81873
0
26,666
<u>Set 1</u>**p1.** Assume the speed of sound is $343$ m/s. Anastasia and Bananastasia are standing in a field in front of you. When they both yell at the same time, you hear Anastasia’s yell $5$ seconds before Bananastasia’s yell. If Bananastasia yells first, and then Anastasia yells when she hears Bananastasia yell, you hear Anastasia’s yell $5$ seconds after Bananastasia’s yell. What is the distance between Anastasia and Bananastasia in meters?**p2.** Michelle picks a five digit number with distinct digits. She then reverses the digits of her number and adds that to her original number. What is the largest possible sum she can get?**p3.** Twain is trying to crack a $4$ -digit number combination lock. They know that the second digit must be even, the third must be odd, and the fourth must be different from the previous three. If it takes Twain $10$ seconds to enter a combination, how many hours would it take them to try every possible combination that satisfies these rules? PS. You should use hide for answers.
1715
11.71875
26,667
Let $n$ be a $5$-digit number, and let $q$ and $r$ be the quotient and the remainder, respectively, when $n$ is divided by $50$. Given that $q$ is an even number, determine the number of values of $n$ for which $q - r$ is divisible by $7$.
7200
0.78125
26,668
If a non-negative integer \( m \) and the sum of its digits are both multiples of 6, then \( m \) is called a "Liuhe number." Find the number of Liuhe numbers less than 2012.
168
99.21875
26,669
Among the three-digit numbers composed of the digits $0$ to $9$, the number of numbers where the digits are arranged in strictly increasing or strictly decreasing order, calculate the total.
204
29.6875
26,670
Using the digits 0 to 9, how many three-digit even numbers can be formed without repeating any digits?
360
0.78125
26,671
Given an ellipse $C$: $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 (a > b > 0)$, where the upper vertex of $C$ is $A$, and the two foci are $F_{1}$ and $F_{2}$, with an eccentricity of $\frac{1}{2}$. A line passing through $F_{1}$ and perpendicular to $AF_{2}$ intersects $C$ at points $D$ and $E$, where $|DE| = 6$. Find the perimeter of $\triangle ADE$.
13
14.84375
26,672
In the Cartesian coordinate system xOy, the equation of line l is given as x+1=0, and curve C is a parabola with the coordinate origin O as the vertex and line l as the axis. Establish a polar coordinate system with the coordinate origin O as the pole and the non-negative semi-axis of the x-axis as the polar axis. 1. Find the polar coordinate equations for line l and curve C respectively. 2. Point A is a moving point on curve C in the first quadrant, and point B is a moving point on line l in the second quadrant. If ∠AOB=$$\frac {π}{4}$$, find the maximum value of $$\frac {|OA|}{|OB|}$$.
\frac { \sqrt {2}}{2}
0
26,673
Seven cards numbered $1$ through $7$ are to be lined up in a row. Find the number of arrangements of these seven cards where one of the cards can be removed leaving the remaining six cards in either ascending or descending order.
74
0
26,674
If I have a $5\times5$ chess board, in how many ways can I place five distinct pawns on the board such that each column and row of the board contains no more than one pawn?
14400
0
26,675
Let $AB$ be a segment of length $2$ . The locus of points $P$ such that the $P$ -median of triangle $ABP$ and its reflection over the $P$ -angle bisector of triangle $ABP$ are perpendicular determines some region $R$ . Find the area of $R$ .
2\pi
12.5
26,676
In the book "The Nine Chapters on the Mathematical Art," a right square pyramid, whose base is a rectangle and has a side edge perpendicular to the base, is called a "yangma." Given a right square pyramid $M-ABCD$, where side edge $MA$ is perpendicular to the base $ABCD$, and $MA = BC = AB = 2$, calculate the sum of the surface areas of the inscribed and circumscribed spheres.
36\pi - 16\sqrt{2}\pi
0
26,677
A regular hexagon $ABCDEF$ has sides of length three. Find the area of $\bigtriangleup ACE$. Express your answer in simplest radical form.
\frac{9\sqrt{3}}{4}
1.5625
26,678
If \[ 1 \cdot 1995 + 2 \cdot 1994 + 3 \cdot 1993 + \dots + 1994 \cdot 2 + 1995 \cdot 1 = 1995 \cdot 997 \cdot y, \] compute the integer \( y \).
665
14.84375
26,679
Through points \(A(0, 14)\) and \(B(0, 4)\), two parallel lines are drawn. The first line, passing through point \(A\), intersects the hyperbola \(y = \frac{1}{x}\) at points \(K\) and \(L\). The second line, passing through point \(B\), intersects the hyperbola \(y = \frac{1}{x}\) at points \(M\) and \(N\). What is the value of \(\frac{AL - AK}{BN - BM}\)?
3.5
3.125
26,680
In a square, points $R$ and $S$ are midpoints of two adjacent sides. A line segment is drawn from the bottom left vertex to point $S$, and another from the top right vertex to point $R$. What fraction of the interior of the square is shaded? [asy] filldraw((0,0)--(2,0)--(2,2)--(0,2)--(0,0)--gray,linewidth(1)); filldraw((0,1)--(1,2)--(2,1)--(1,0)--(0,1)--cycle,white,linewidth(1)); label("R",(0,1),W); label("S",(1,2),N); [/asy]
\frac{3}{4}
7.03125
26,681
Let $2005 = c_1 \cdot 3^{a_1} + c_2 \cdot 3^{a_2} + \ldots + c_n \cdot 3^{a_n}$, where $n$ is a positive integer, $a_1, a_2, \ldots, a_n$ are distinct natural numbers (including 0, with the convention that $3^0 = 1$), and each of $c_1, c_2, \ldots, c_n$ is equal to 1 or -1. Find the sum $a_1 + a_2 + \ldots + a_n$.
22
12.5
26,682
There are two boxes, A and B, each containing four cards labeled with the numbers 1, 2, 3, and 4. One card is drawn from each box, and each card is equally likely to be chosen; (I) Find the probability that the product of the numbers on the two cards drawn is divisible by 3; (II) Suppose that Xiao Wang and Xiao Li draw two cards, and the person whose sum of the numbers on the two cards is greater wins. If Xiao Wang goes first and draws cards numbered 3 and 4, and the cards drawn by Xiao Wang are not returned to the boxes, Xiao Li draws next; find the probability that Xiao Wang wins.
\frac{8}{9}
3.90625
26,683
Given that $\tbinom{n}{k}=\tfrac{n!}{k!(n-k)!}$ , the value of $$ \sum_{n=3}^{10}\frac{\binom{n}{2}}{\binom{n}{3}\binom{n+1}{3}} $$ can be written in the form $\tfrac{m}{n}$ , where $m$ and $n$ are relatively prime positive integers. Compute $m+n$ .
329
1.5625
26,684
Given a triangle $\triangle ABC$ with sides $a$, $b$, $c$ opposite to angles $A$, $B$, $C$ respectively. If $a=2$, $A= \frac{\pi}{3}$, and $\frac{\sqrt{3}}{2} - \sin(B-C) = \sin 2B$, find the area of $\triangle ABC$.
\frac{2\sqrt{3}}{3}
28.125
26,685
In the diagram, \(PR, PS, QS, QT,\) and \(RT\) are straight line segments. \(QT\) intersects \(PR\) and \(PS\) at \(U\) and \(V\), respectively. If \(PU = PV\), \(\angle UPV = 24^\circ\), \(\angle PSQ = x^\circ\), and \(\angle TQS = y^\circ\), what is the value of \(x + y\)?
78
10.15625
26,686
Given 6 parking spaces in a row and 3 cars that need to be parked such that no two cars are next to each other, calculate the number of different parking methods.
24
89.0625
26,687
Distribute 4 college students to three factories A, B, and C for internship activities. Factory A can only arrange for 1 college student, the other factories must arrange for at least 1 student each, and student A cannot be assigned to factory C. The number of different distribution schemes is ______.
12
8.59375
26,688
Roll three dice once each, and let event A be "the three numbers are all different," and event B be "at least one 1 is rolled." Then the conditional probabilities P(A|B) and P(B|A) are respectively ( ).
\frac{1}{2}
21.09375
26,689
Given vectors $\overrightarrow {OA} = (1, -2)$, $\overrightarrow {OB} = (4, -1)$, $\overrightarrow {OC} = (m, m+1)$. (1) If $\overrightarrow {AB} \parallel \overrightarrow {OC}$, find the value of the real number $m$; (2) If $\triangle ABC$ is a right-angled triangle, find the value of the real number $m$.
\frac{5}{2}
42.1875
26,690
The sum of an infinite geometric series is $81$ times the series that results if the first five terms of the original series are removed. What is the value of the series' common ratio?
\frac{1}{3}
67.1875
26,691
The lengths of the six edges of a tetrahedron \(ABCD\) are 7, 13, 18, 27, 36, and 41, respectively. If \(AB = 41\), what is the length of \(CD\)?
13
73.4375
26,692
Let $S$ be the set of all non-zero real numbers. Define a function $f : S \to S$ such that for all $x, y \in S$ with $x + y \neq 0$, the following holds: \[f(x) + f(y) = f\left(\frac{xy}{x+y}f(x+y)\right).\] Determine the number of possible values of $f(3)$, denoted as $n$, and the sum of all possible values of $f(3)$, denoted as $s$. Finally, compute $n \times s$.
\frac{1}{3}
15.625
26,693
Points \( A \) and \( B \) are located on a straight highway running from west to east. Point \( B \) is 9 km east of \( A \). A car leaves point \( A \) heading east at a speed of 40 km/h. At the same time, a motorcycle leaves point \( B \) in the same direction with a constant acceleration of 32 km/h\(^2\). Determine the maximum distance between the car and the motorcycle during the first two hours of their journey.
25
3.90625
26,694
Fill in the blanks with numbers $1 \sim 3$, so that each row and each column contains exactly one number appearing twice. The numbers outside the table indicate how many numbers are visible from that direction. A number can block equal or smaller numbers. What is the four-digit number $\overline{\mathrm{ABCD}}$?
2213
0
26,695
Let $P$ be a point not on line $XZ$ and $Q$ a point on line $XZ$ such that $PQ \perp XZ.$ Meanwhile, $R$ is a point on line $PZ$ such that $SR \perp PZ.$ If $SR = 5,$ $PQ = 6,$ and $XZ = 7,$ then what is the length of $PZ?$
8.4
5.46875
26,696
From a school of 2100 students, a sample of 30 students is randomly selected. The time (in minutes) each student spends on homework outside of class is as follows: 75, 80, 85, 65, 95, 100, 70, 55, 65, 75, 85, 110, 120, 80, 85, 80, 75, 90, 90, 95, 70, 60, 60, 75, 90, 95, 65, 75, 80, 80. The number of students in this school who spend more than or equal to one and a half hours on homework outside of class is $\boxed{\text{\_\_\_\_\_\_\_\_}}$.
630
77.34375
26,697
Compute the value of $\left(81\right)^{0.25} \cdot \left(81\right)^{0.2}$.
3 \cdot \sqrt[5]{3^4}
0
26,698
Given that $F(1,0)$ is the focus of the ellipse $\frac{x^2}{9} + \frac{y^2}{m} = 1$, $P$ is a moving point on the ellipse, and $A(1,1)$, find the minimum value of $|PA| + |PF|$.
6 - \sqrt{5}
41.40625
26,699
Mady now has boxes each capable of holding up to 5 balls instead of 4. Under the same process as described, Mady adds balls and resets boxes. Determine the total number of balls in the boxes after her $2010$th step.
10
14.0625