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**seercalf****Member**- Registered: 2019-10-13
- Posts: 17

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?

"Nothing is better than learning and gaining more and more knowledge." _ Stephen Hawking

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**Relentless****Member**- Registered: 2015-12-15
- Posts: 631

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)*

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