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A password of a computer used five digits where they are fro

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by Sionainn@PrincetonReview » Wed May 09, 2018 11:27 am
You are correct. To find the probability find the number of passwords that meet the requirement and put that over the total number of possibilities. There are 5 digits that meet the requirement of prime numbers or zero: 0, 2, 3, 5 and 7. So the number of five-digit passwords that meet this requirement is 5*5*5*5*5. Since we're choosing from 10 possible digits, the total number of five-digit passwords is 10*10*10*10*10. When you put (5*5*5*5*5)/(10*10*10*10*10), you can cancel out all of the 5's to get 1/(2*2*2*2*2) or 1/32 or A.

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by Scott@TargetTestPrep » Thu May 10, 2018 4:55 pm
harshitpuri wrote:A password of a computer used five digits where they are from 0 and 9. What is the probability that the password solely consists of prime numbers and zero?
A 1/32
B 1/16
C 1/8
D 2/5
E ½
The total number of ways to select 5 digits to form a 5-digit password is 10^5. The number of ways to select the 5 digits that are either a prime (2, 3, 5, 7) or zero is 5^5. Therefore, the probability is 5^5/10^5 = (5/10)^5 = (1/2)^5 = 1/32.

Answer: A

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