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7 come zero (Posted on 2018-06-28) Difficulty: 3 of 5
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)

Comments: ( Back to comment list | You must be logged in to post comments.)
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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