perplexus.info :: Probability : 7 come zero

7 come zero (Posted on 2018-06-28)

Let N be a randomly chosen 5-digit number.

a. What is the probability that N contains at least one zero?
b. What is the probability that N contains at least one 7?
c. What is the probability that it contains exactly one zero and one 7?

d. Generalize the above questions for a n-digit number , n>1.

No Solution Yet Submitted by Ady TZIDON

Rating: 5.0000 (1 votes)

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First thoughts (spoiler-ish)

| Comment 1 of 5

a. P(no zeros) = (9/10)^5 => P(at least 1 zero) = 1 - (9/10)^5

b. P(at least one 7) = P(at least 1 zero) = 1 - (9/10)^5

c. and d. Need to cogitate on these over first cup of Java . . .

Posted by JayDeeKay on 2018-06-28 08:23:36

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