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प्रश्न
A box has 100 pens of which 10 are defective. What is the probability that out of a sample of 5 pens drawn one by one with replacement at most one is defective?
विकल्प
`(9/10)^5`
`1/2(9/10)^4`
`1/2(9/10)^5`
`(9/10)^5 + 1/2(9/10)^4`
उत्तर
`(9/10)^5 + 1/2(9/10)^4`
Explanation:
Here, n = 5
p = `10/100 = 1/10` and q = `1 - 1/10 = 9/10` and r ≤ 1
We know that
P(X = r) = `""^"n""C"_"r" "p"^"r" "q"^("n" - "r")`
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