Math Is Fun Forum

seercalf

Member

Registered: 2019-10-13

Posts: 17

Probability and Statistics

10 cards are numbered from 1 to 10 and placed in a box. One card is selected at random and is not replaced. Another card is then randomly selected. What is the probability of selecting two prime numbers?

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Relentless

Member

Registered: 2015-12-15

Posts: 631

Re: Probability and Statistics

There are 9*10=90 possible combinations. There are 3*4=12 possible prime number combinations: (2,3), (2,5), (2,7), (3,2), (3,5), (3,7), (5,2), (5,3), (5,7), (7,2), (7,3), (7,5). The probability is 12/90=2/15.

Last edited by Relentless (2019-10-17 23:46:17)