NCERT Class XII Mathematics Chapter - - Solutions

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Question : 73
Total: 101
A bag consists of 10 balls each marked with one of the digits 0 to 9. If four balls are drawn successively with replacement from the bag, what is the probability that none is marked with the digit 0 ?
Solution:  
The probability of ball with digit 0 is drawn =
1
10

let p be the probability of success =
1
10

X has the binomial distribution with n=4,p=
1
10
,q=
9
10

P(X=r)=nCr(q)nrpr
∴ P (none is marked with 0) = P(X = 0)
=4C0q4p0 =1×(
9
10
)
4
×1
=(
9
10
)
4
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