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1
7518-7521
Clearly, six different cases are there as listed below: SFFFFF, FSFFFF, FFSFFF, FFFSFF, FFFFSF, FFFFFS Similarly, two successes and four failures can have 6 4 2
1
7519-7522
Similarly, two successes and four failures can have 6 4 2 combinations
1
7520-7523
4 2 combinations It will be lengthy job to list all of these ways
1
7521-7524
2 combinations It will be lengthy job to list all of these ways Therefore, calculation of probabilities of 0, 1, 2,
1
7522-7525
combinations It will be lengthy job to list all of these ways Therefore, calculation of probabilities of 0, 1, 2, , n number of successes may be lengthy and time consuming
1
7523-7526
It will be lengthy job to list all of these ways Therefore, calculation of probabilities of 0, 1, 2, , n number of successes may be lengthy and time consuming To avoid the lengthy calculations and listing of all the possible cases, for the probabilities of number of successes in n-Bernoulli trials, a formula is derived
1
7524-7527
Therefore, calculation of probabilities of 0, 1, 2, , n number of successes may be lengthy and time consuming To avoid the lengthy calculations and listing of all the possible cases, for the probabilities of number of successes in n-Bernoulli trials, a formula is derived For this purpose, let us take the experiment made up of three Bernoulli trials with probabilities p and q = 1 – p for success and failure respectively in each trial
1
7525-7528
, n number of successes may be lengthy and time consuming To avoid the lengthy calculations and listing of all the possible cases, for the probabilities of number of successes in n-Bernoulli trials, a formula is derived For this purpose, let us take the experiment made up of three Bernoulli trials with probabilities p and q = 1 – p for success and failure respectively in each trial The sample space of the experiment is the set S = {SSS, SSF, SFS, FSS, SFF, FSF, FFS, FFF} The number of successes is a random variable X and can take values 0, 1, 2, or 3
1
7526-7529
To avoid the lengthy calculations and listing of all the possible cases, for the probabilities of number of successes in n-Bernoulli trials, a formula is derived For this purpose, let us take the experiment made up of three Bernoulli trials with probabilities p and q = 1 – p for success and failure respectively in each trial The sample space of the experiment is the set S = {SSS, SSF, SFS, FSS, SFF, FSF, FFS, FFF} The number of successes is a random variable X and can take values 0, 1, 2, or 3 The probability distribution of the number of successes is as below : P(X = 0) = P(no success) = P({FFF}) = P(F) P(F) P(F) = q
1
7527-7530
For this purpose, let us take the experiment made up of three Bernoulli trials with probabilities p and q = 1 – p for success and failure respectively in each trial The sample space of the experiment is the set S = {SSS, SSF, SFS, FSS, SFF, FSF, FFS, FFF} The number of successes is a random variable X and can take values 0, 1, 2, or 3 The probability distribution of the number of successes is as below : P(X = 0) = P(no success) = P({FFF}) = P(F) P(F) P(F) = q q
1
7528-7531
The sample space of the experiment is the set S = {SSS, SSF, SFS, FSS, SFF, FSF, FFS, FFF} The number of successes is a random variable X and can take values 0, 1, 2, or 3 The probability distribution of the number of successes is as below : P(X = 0) = P(no success) = P({FFF}) = P(F) P(F) P(F) = q q q = q3 since the trials are independent P(X = 1) = P(one successes) = P({SFF, FSF, FFS}) = P({SFF}) + P({FSF}) + P({FFS}) = P(S) P(F) P(F) + P(F) P(S) P(F) + P(F) P(F) P(S) = p
1
7529-7532
The probability distribution of the number of successes is as below : P(X = 0) = P(no success) = P({FFF}) = P(F) P(F) P(F) = q q q = q3 since the trials are independent P(X = 1) = P(one successes) = P({SFF, FSF, FFS}) = P({SFF}) + P({FSF}) + P({FFS}) = P(S) P(F) P(F) + P(F) P(S) P(F) + P(F) P(F) P(S) = p q
1
7530-7533
q q = q3 since the trials are independent P(X = 1) = P(one successes) = P({SFF, FSF, FFS}) = P({SFF}) + P({FSF}) + P({FFS}) = P(S) P(F) P(F) + P(F) P(S) P(F) + P(F) P(F) P(S) = p q q + q
1
7531-7534
q = q3 since the trials are independent P(X = 1) = P(one successes) = P({SFF, FSF, FFS}) = P({SFF}) + P({FSF}) + P({FFS}) = P(S) P(F) P(F) + P(F) P(S) P(F) + P(F) P(F) P(S) = p q q + q p
1
7532-7535
q q + q p q + q
1
7533-7536
q + q p q + q q
1
7534-7537
p q + q q p = 3pq2 P(X = 2) = P (two successes) = P({SSF, SFS, FSS}) = P({SSF}) + P ({SFS}) + P({FSS}) Β© NCERT not to be republished 574 MATHEMATICS = P(S) P(S) P(F) + P(S) P(F) P(S) + P(F) P(S) P(S) = p
1
7535-7538
q + q q p = 3pq2 P(X = 2) = P (two successes) = P({SSF, SFS, FSS}) = P({SSF}) + P ({SFS}) + P({FSS}) Β© NCERT not to be republished 574 MATHEMATICS = P(S) P(S) P(F) + P(S) P(F) P(S) + P(F) P(S) P(S) = p p
1
7536-7539
q p = 3pq2 P(X = 2) = P (two successes) = P({SSF, SFS, FSS}) = P({SSF}) + P ({SFS}) + P({FSS}) Β© NCERT not to be republished 574 MATHEMATICS = P(S) P(S) P(F) + P(S) P(F) P(S) + P(F) P(S) P(S) = p p q
1
7537-7540
p = 3pq2 P(X = 2) = P (two successes) = P({SSF, SFS, FSS}) = P({SSF}) + P ({SFS}) + P({FSS}) Β© NCERT not to be republished 574 MATHEMATICS = P(S) P(S) P(F) + P(S) P(F) P(S) + P(F) P(S) P(S) = p p q + p
1
7538-7541
p q + p q
1
7539-7542
q + p q p + q
1
7540-7543
+ p q p + q p
1
7541-7544
q p + q p p = 3p2q and P(X = 3) = P(three success) = P ({SSS}) = P(S)
1
7542-7545
p + q p p = 3p2q and P(X = 3) = P(three success) = P ({SSS}) = P(S) P(S)
1
7543-7546
p p = 3p2q and P(X = 3) = P(three success) = P ({SSS}) = P(S) P(S) P(S) = p3 Thus, the probability distribution of X is X 0 1 2 3 P(X) q 3 3q2p 3qp2 p 3 Also, the binominal expansion of (q + p)3 is q q p qp p 3 3 2 3 2 3 + + + Note that the probabilities of 0, 1, 2 or 3 successes are respectively the 1st, 2nd, 3rd and 4th term in the expansion of (q + p)3
1
7544-7547
p = 3p2q and P(X = 3) = P(three success) = P ({SSS}) = P(S) P(S) P(S) = p3 Thus, the probability distribution of X is X 0 1 2 3 P(X) q 3 3q2p 3qp2 p 3 Also, the binominal expansion of (q + p)3 is q q p qp p 3 3 2 3 2 3 + + + Note that the probabilities of 0, 1, 2 or 3 successes are respectively the 1st, 2nd, 3rd and 4th term in the expansion of (q + p)3 Also, since q + p = 1, it follows that the sum of these probabilities, as expected, is 1
1
7545-7548
P(S) P(S) = p3 Thus, the probability distribution of X is X 0 1 2 3 P(X) q 3 3q2p 3qp2 p 3 Also, the binominal expansion of (q + p)3 is q q p qp p 3 3 2 3 2 3 + + + Note that the probabilities of 0, 1, 2 or 3 successes are respectively the 1st, 2nd, 3rd and 4th term in the expansion of (q + p)3 Also, since q + p = 1, it follows that the sum of these probabilities, as expected, is 1 Thus, we may conclude that in an experiment of n-Bernoulli trials, the probabilities of 0, 1, 2,
1
7546-7549
P(S) = p3 Thus, the probability distribution of X is X 0 1 2 3 P(X) q 3 3q2p 3qp2 p 3 Also, the binominal expansion of (q + p)3 is q q p qp p 3 3 2 3 2 3 + + + Note that the probabilities of 0, 1, 2 or 3 successes are respectively the 1st, 2nd, 3rd and 4th term in the expansion of (q + p)3 Also, since q + p = 1, it follows that the sum of these probabilities, as expected, is 1 Thus, we may conclude that in an experiment of n-Bernoulli trials, the probabilities of 0, 1, 2, , n successes can be obtained as 1st, 2nd,
1
7547-7550
Also, since q + p = 1, it follows that the sum of these probabilities, as expected, is 1 Thus, we may conclude that in an experiment of n-Bernoulli trials, the probabilities of 0, 1, 2, , n successes can be obtained as 1st, 2nd, ,(n + 1)th terms in the expansion of (q + p)n
1
7548-7551
Thus, we may conclude that in an experiment of n-Bernoulli trials, the probabilities of 0, 1, 2, , n successes can be obtained as 1st, 2nd, ,(n + 1)th terms in the expansion of (q + p)n To prove this assertion (result), let us find the probability of x-successes in an experiment of n-Bernoulli trials
1
7549-7552
, n successes can be obtained as 1st, 2nd, ,(n + 1)th terms in the expansion of (q + p)n To prove this assertion (result), let us find the probability of x-successes in an experiment of n-Bernoulli trials Clearly, in case of x successes (S), there will be (n – x) failures (F)
1
7550-7553
,(n + 1)th terms in the expansion of (q + p)n To prove this assertion (result), let us find the probability of x-successes in an experiment of n-Bernoulli trials Clearly, in case of x successes (S), there will be (n – x) failures (F) Now, x successes (S) and (n – x) failures (F) can be obtained in
1
7551-7554
To prove this assertion (result), let us find the probability of x-successes in an experiment of n-Bernoulli trials Clearly, in case of x successes (S), there will be (n – x) failures (F) Now, x successes (S) and (n – x) failures (F) can be obtained in (
1
7552-7555
Clearly, in case of x successes (S), there will be (n – x) failures (F) Now, x successes (S) and (n – x) failures (F) can be obtained in ( )
1
7553-7556
Now, x successes (S) and (n – x) failures (F) can be obtained in ( ) n x n x ways
1
7554-7557
( ) n x n x ways In each of these ways, the probability of x successes and (n βˆ’ x) failures is = P(x successes)
1
7555-7558
) n x n x ways In each of these ways, the probability of x successes and (n βˆ’ x) failures is = P(x successes) P(n–x) failures is = times ( ) times P(S)
1
7556-7559
n x n x ways In each of these ways, the probability of x successes and (n βˆ’ x) failures is = P(x successes) P(n–x) failures is = times ( ) times P(S) P(S)
1
7557-7560
In each of these ways, the probability of x successes and (n βˆ’ x) failures is = P(x successes) P(n–x) failures is = times ( ) times P(S) P(S) P(S) P(F)
1
7558-7561
P(n–x) failures is = times ( ) times P(S) P(S) P(S) P(F) P(F)
1
7559-7562
P(S) P(S) P(F) P(F) P(F) x n x 1442443 1442443 = px qn–x Thus, the probability of x successes in n-Bernoulli trials is
1
7560-7563
P(S) P(F) P(F) P(F) x n x 1442443 1442443 = px qn–x Thus, the probability of x successes in n-Bernoulli trials is (
1
7561-7564
P(F) P(F) x n x 1442443 1442443 = px qn–x Thus, the probability of x successes in n-Bernoulli trials is ( )
1
7562-7565
P(F) x n x 1442443 1442443 = px qn–x Thus, the probability of x successes in n-Bernoulli trials is ( ) n x n βˆ’x px qn–x or nCx px qn–x Thus P(x successes) = nC x n x x p q βˆ’ , x = 0, 1, 2,
1
7563-7566
( ) n x n βˆ’x px qn–x or nCx px qn–x Thus P(x successes) = nC x n x x p q βˆ’ , x = 0, 1, 2, ,n
1
7564-7567
) n x n βˆ’x px qn–x or nCx px qn–x Thus P(x successes) = nC x n x x p q βˆ’ , x = 0, 1, 2, ,n (q = 1 – p) Clearly, P(x successes), i
1
7565-7568
n x n βˆ’x px qn–x or nCx px qn–x Thus P(x successes) = nC x n x x p q βˆ’ , x = 0, 1, 2, ,n (q = 1 – p) Clearly, P(x successes), i e
1
7566-7569
,n (q = 1 – p) Clearly, P(x successes), i e C n x n x x p q βˆ’ is the (x + 1)th term in the binomial expansion of (q + p)n
1
7567-7570
(q = 1 – p) Clearly, P(x successes), i e C n x n x x p q βˆ’ is the (x + 1)th term in the binomial expansion of (q + p)n Thus, the probability distribution of number of successes in an experiment consisting of n Bernoulli trials may be obtained by the binomial expansion of (q + p)n
1
7568-7571
e C n x n x x p q βˆ’ is the (x + 1)th term in the binomial expansion of (q + p)n Thus, the probability distribution of number of successes in an experiment consisting of n Bernoulli trials may be obtained by the binomial expansion of (q + p)n Hence, this Β© NCERT not to be republished PROBABILITY 575 distribution of number of successes X can be written as X 0 1 2
1
7569-7572
C n x n x x p q βˆ’ is the (x + 1)th term in the binomial expansion of (q + p)n Thus, the probability distribution of number of successes in an experiment consisting of n Bernoulli trials may be obtained by the binomial expansion of (q + p)n Hence, this Β© NCERT not to be republished PROBABILITY 575 distribution of number of successes X can be written as X 0 1 2 x
1
7570-7573
Thus, the probability distribution of number of successes in an experiment consisting of n Bernoulli trials may be obtained by the binomial expansion of (q + p)n Hence, this Β© NCERT not to be republished PROBABILITY 575 distribution of number of successes X can be written as X 0 1 2 x n P(X) nC0 qn nC1 qn–1p1 nC2 qn–2p2 nCx qn–xpx nCn pn The above probability distribution is known as binomial distribution with parameters n and p, because for given values of n and p, we can find the complete probability distribution
1
7571-7574
Hence, this Β© NCERT not to be republished PROBABILITY 575 distribution of number of successes X can be written as X 0 1 2 x n P(X) nC0 qn nC1 qn–1p1 nC2 qn–2p2 nCx qn–xpx nCn pn The above probability distribution is known as binomial distribution with parameters n and p, because for given values of n and p, we can find the complete probability distribution The probability of x successes P(X = x) is also denoted by P(x) and is given by P(x) = nCx qn–xpx, x = 0, 1,
1
7572-7575
x n P(X) nC0 qn nC1 qn–1p1 nC2 qn–2p2 nCx qn–xpx nCn pn The above probability distribution is known as binomial distribution with parameters n and p, because for given values of n and p, we can find the complete probability distribution The probability of x successes P(X = x) is also denoted by P(x) and is given by P(x) = nCx qn–xpx, x = 0, 1, , n
1
7573-7576
n P(X) nC0 qn nC1 qn–1p1 nC2 qn–2p2 nCx qn–xpx nCn pn The above probability distribution is known as binomial distribution with parameters n and p, because for given values of n and p, we can find the complete probability distribution The probability of x successes P(X = x) is also denoted by P(x) and is given by P(x) = nCx qn–xpx, x = 0, 1, , n (q = 1 – p) This P(x) is called the probability function of the binomial distribution
1
7574-7577
The probability of x successes P(X = x) is also denoted by P(x) and is given by P(x) = nCx qn–xpx, x = 0, 1, , n (q = 1 – p) This P(x) is called the probability function of the binomial distribution A binomial distribution with n-Bernoulli trials and probability of success in each trial as p, is denoted by B(n, p)
1
7575-7578
, n (q = 1 – p) This P(x) is called the probability function of the binomial distribution A binomial distribution with n-Bernoulli trials and probability of success in each trial as p, is denoted by B(n, p) Let us now take up some examples
1
7576-7579
(q = 1 – p) This P(x) is called the probability function of the binomial distribution A binomial distribution with n-Bernoulli trials and probability of success in each trial as p, is denoted by B(n, p) Let us now take up some examples Example 31 If a fair coin is tossed 10 times, find the probability of (i) exactly six heads (ii) at least six heads (iii) at most six heads Solution The repeated tosses of a coin are Bernoulli trials
1
7577-7580
A binomial distribution with n-Bernoulli trials and probability of success in each trial as p, is denoted by B(n, p) Let us now take up some examples Example 31 If a fair coin is tossed 10 times, find the probability of (i) exactly six heads (ii) at least six heads (iii) at most six heads Solution The repeated tosses of a coin are Bernoulli trials Let X denote the number of heads in an experiment of 10 trials
1
7578-7581
Let us now take up some examples Example 31 If a fair coin is tossed 10 times, find the probability of (i) exactly six heads (ii) at least six heads (iii) at most six heads Solution The repeated tosses of a coin are Bernoulli trials Let X denote the number of heads in an experiment of 10 trials Clearly, X has the binomial distribution with n = 10 and p = 1 2 Therefore P(X = x) = nCxqn–xpx, x = 0, 1, 2,
1
7579-7582
Example 31 If a fair coin is tossed 10 times, find the probability of (i) exactly six heads (ii) at least six heads (iii) at most six heads Solution The repeated tosses of a coin are Bernoulli trials Let X denote the number of heads in an experiment of 10 trials Clearly, X has the binomial distribution with n = 10 and p = 1 2 Therefore P(X = x) = nCxqn–xpx, x = 0, 1, 2, ,n Here n = 10, 21 p , q = 1 – p = 1 2 Therefore P(X = x) = 10 10 10 10 1 1 1 C C 2 2 2 x x x x βˆ’ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ = ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ Now (i) P(X = 6) = 10 10 6 10 1 10
1
7580-7583
Let X denote the number of heads in an experiment of 10 trials Clearly, X has the binomial distribution with n = 10 and p = 1 2 Therefore P(X = x) = nCxqn–xpx, x = 0, 1, 2, ,n Here n = 10, 21 p , q = 1 – p = 1 2 Therefore P(X = x) = 10 10 10 10 1 1 1 C C 2 2 2 x x x x βˆ’ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ = ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ Now (i) P(X = 6) = 10 10 6 10 1 10 1 105 C 2 6
1
7581-7584
Clearly, X has the binomial distribution with n = 10 and p = 1 2 Therefore P(X = x) = nCxqn–xpx, x = 0, 1, 2, ,n Here n = 10, 21 p , q = 1 – p = 1 2 Therefore P(X = x) = 10 10 10 10 1 1 1 C C 2 2 2 x x x x βˆ’ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ = ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ Now (i) P(X = 6) = 10 10 6 10 1 10 1 105 C 2 6 4
1
7582-7585
,n Here n = 10, 21 p , q = 1 – p = 1 2 Therefore P(X = x) = 10 10 10 10 1 1 1 C C 2 2 2 x x x x βˆ’ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ = ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ Now (i) P(X = 6) = 10 10 6 10 1 10 1 105 C 2 6 4 512 2 βŽ› ⎞ = = ⎜ ⎟ Γ— ⎝ ⎠ (ii) P(at least six heads) = P(X β‰₯ 6) = P (X = 6) + P (X = 7) + P (X = 8) + P(X = 9) + P (X = 10) Β© NCERT not to be republished 576 MATHEMATICS = 10 10 10 10 10 10 10 10 10 10 6 7 8 9 10 1 1 1 1 1 C C C C C 2 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 10 10
1
7583-7586
1 105 C 2 6 4 512 2 βŽ› ⎞ = = ⎜ ⎟ Γ— ⎝ ⎠ (ii) P(at least six heads) = P(X β‰₯ 6) = P (X = 6) + P (X = 7) + P (X = 8) + P(X = 9) + P (X = 10) Β© NCERT not to be republished 576 MATHEMATICS = 10 10 10 10 10 10 10 10 10 10 6 7 8 9 10 1 1 1 1 1 C C C C C 2 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 10 10 10
1
7584-7587
4 512 2 βŽ› ⎞ = = ⎜ ⎟ Γ— ⎝ ⎠ (ii) P(at least six heads) = P(X β‰₯ 6) = P (X = 6) + P (X = 7) + P (X = 8) + P(X = 9) + P (X = 10) Β© NCERT not to be republished 576 MATHEMATICS = 10 10 10 10 10 10 10 10 10 10 6 7 8 9 10 1 1 1 1 1 C C C C C 2 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 10 10 10 10
1
7585-7588
512 2 βŽ› ⎞ = = ⎜ ⎟ Γ— ⎝ ⎠ (ii) P(at least six heads) = P(X β‰₯ 6) = P (X = 6) + P (X = 7) + P (X = 8) + P(X = 9) + P (X = 10) Β© NCERT not to be republished 576 MATHEMATICS = 10 10 10 10 10 10 10 10 10 10 6 7 8 9 10 1 1 1 1 1 C C C C C 2 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 10 10 10 10 10
1
7586-7589
10 10 10 10
1
7587-7590
10 10 10 1 6
1
7588-7591
10 10 1 6 4
1
7589-7592
10 1 6 4 7
1
7590-7593
1 6 4 7 3
1
7591-7594
4 7 3 8
1
7592-7595
7 3 8 2
1
7593-7596
3 8 2 9
1
7594-7597
8 2 9 1
1
7595-7598
2 9 1 10
1
7596-7599
9 1 10 2 193 512 = (iii) P(at most six heads) = P(X ≀ 6) = P (X = 0) + P (X = 1) + P (X = 2) + P (X = 3) + P (X = 4) + P (X = 5) + P (X = 6) = 10 10 10 10 10 10 10 1 2 3 1 1 1 1 C C C 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ + 10 10 10 10 10 10 4 5 6 1 1 1 C C C 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 848 53 1024 64 = Example 32 Ten eggs are drawn successively with replacement from a lot containing 10% defective eggs
1
7597-7600
1 10 2 193 512 = (iii) P(at most six heads) = P(X ≀ 6) = P (X = 0) + P (X = 1) + P (X = 2) + P (X = 3) + P (X = 4) + P (X = 5) + P (X = 6) = 10 10 10 10 10 10 10 1 2 3 1 1 1 1 C C C 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ + 10 10 10 10 10 10 4 5 6 1 1 1 C C C 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 848 53 1024 64 = Example 32 Ten eggs are drawn successively with replacement from a lot containing 10% defective eggs Find the probability that there is at least one defective egg
1
7598-7601
10 2 193 512 = (iii) P(at most six heads) = P(X ≀ 6) = P (X = 0) + P (X = 1) + P (X = 2) + P (X = 3) + P (X = 4) + P (X = 5) + P (X = 6) = 10 10 10 10 10 10 10 1 2 3 1 1 1 1 C C C 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ + 10 10 10 10 10 10 4 5 6 1 1 1 C C C 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 848 53 1024 64 = Example 32 Ten eggs are drawn successively with replacement from a lot containing 10% defective eggs Find the probability that there is at least one defective egg Solution Let X denote the number of defective eggs in the 10 eggs drawn
1
7599-7602
2 193 512 = (iii) P(at most six heads) = P(X ≀ 6) = P (X = 0) + P (X = 1) + P (X = 2) + P (X = 3) + P (X = 4) + P (X = 5) + P (X = 6) = 10 10 10 10 10 10 10 1 2 3 1 1 1 1 C C C 2 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ + 10 10 10 10 10 10 4 5 6 1 1 1 C C C 2 2 2 βŽ› ⎞ βŽ› ⎞ βŽ› ⎞ + + ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ = 848 53 1024 64 = Example 32 Ten eggs are drawn successively with replacement from a lot containing 10% defective eggs Find the probability that there is at least one defective egg Solution Let X denote the number of defective eggs in the 10 eggs drawn Since the drawing is done with replacement, the trials are Bernoulli trials
1
7600-7603
Find the probability that there is at least one defective egg Solution Let X denote the number of defective eggs in the 10 eggs drawn Since the drawing is done with replacement, the trials are Bernoulli trials Clearly, X has the binomial distribution with n = 10 and 10 1 100 10 p
1
7601-7604
Solution Let X denote the number of defective eggs in the 10 eggs drawn Since the drawing is done with replacement, the trials are Bernoulli trials Clearly, X has the binomial distribution with n = 10 and 10 1 100 10 p Therefore q = 9 1 βˆ’p10 = Now P(at least one defective egg) = P(X β‰₯ 1) = 1 – P (X = 0) = 10 10 0 9 1 C βŽ›10 ⎞ βˆ’ ⎜ ⎟ ⎝ ⎠ = 10 910 1 10 βˆ’ EXERCISE 13
1
7602-7605
Since the drawing is done with replacement, the trials are Bernoulli trials Clearly, X has the binomial distribution with n = 10 and 10 1 100 10 p Therefore q = 9 1 βˆ’p10 = Now P(at least one defective egg) = P(X β‰₯ 1) = 1 – P (X = 0) = 10 10 0 9 1 C βŽ›10 ⎞ βˆ’ ⎜ ⎟ ⎝ ⎠ = 10 910 1 10 βˆ’ EXERCISE 13 5 1
1
7603-7606
Clearly, X has the binomial distribution with n = 10 and 10 1 100 10 p Therefore q = 9 1 βˆ’p10 = Now P(at least one defective egg) = P(X β‰₯ 1) = 1 – P (X = 0) = 10 10 0 9 1 C βŽ›10 ⎞ βˆ’ ⎜ ⎟ ⎝ ⎠ = 10 910 1 10 βˆ’ EXERCISE 13 5 1 A die is thrown 6 times
1
7604-7607
Therefore q = 9 1 βˆ’p10 = Now P(at least one defective egg) = P(X β‰₯ 1) = 1 – P (X = 0) = 10 10 0 9 1 C βŽ›10 ⎞ βˆ’ ⎜ ⎟ ⎝ ⎠ = 10 910 1 10 βˆ’ EXERCISE 13 5 1 A die is thrown 6 times If β€˜getting an odd number’ is a success, what is the probability of (i) 5 successes
1
7605-7608
5 1 A die is thrown 6 times If β€˜getting an odd number’ is a success, what is the probability of (i) 5 successes (ii) at least 5 successes
1
7606-7609
A die is thrown 6 times If β€˜getting an odd number’ is a success, what is the probability of (i) 5 successes (ii) at least 5 successes (iii) at most 5 successes
1
7607-7610
If β€˜getting an odd number’ is a success, what is the probability of (i) 5 successes (ii) at least 5 successes (iii) at most 5 successes Β© NCERT not to be republished PROBABILITY 577 2
1
7608-7611
(ii) at least 5 successes (iii) at most 5 successes Β© NCERT not to be republished PROBABILITY 577 2 A pair of dice is thrown 4 times
1
7609-7612
(iii) at most 5 successes Β© NCERT not to be republished PROBABILITY 577 2 A pair of dice is thrown 4 times If getting a doublet is considered a success, find the probability of two successes
1
7610-7613
Β© NCERT not to be republished PROBABILITY 577 2 A pair of dice is thrown 4 times If getting a doublet is considered a success, find the probability of two successes 3
1
7611-7614
A pair of dice is thrown 4 times If getting a doublet is considered a success, find the probability of two successes 3 There are 5% defective items in a large bulk of items
1
7612-7615
If getting a doublet is considered a success, find the probability of two successes 3 There are 5% defective items in a large bulk of items What is the probability that a sample of 10 items will include not more than one defective item
1
7613-7616
3 There are 5% defective items in a large bulk of items What is the probability that a sample of 10 items will include not more than one defective item 4
1
7614-7617
There are 5% defective items in a large bulk of items What is the probability that a sample of 10 items will include not more than one defective item 4 Five cards are drawn successively with replacement from a well-shuffled deck of 52 cards
1
7615-7618
What is the probability that a sample of 10 items will include not more than one defective item 4 Five cards are drawn successively with replacement from a well-shuffled deck of 52 cards What is the probability that (i) all the five cards are spades
1
7616-7619
4 Five cards are drawn successively with replacement from a well-shuffled deck of 52 cards What is the probability that (i) all the five cards are spades (ii) only 3 cards are spades
1
7617-7620
Five cards are drawn successively with replacement from a well-shuffled deck of 52 cards What is the probability that (i) all the five cards are spades (ii) only 3 cards are spades (iii) none is a spade