Question

If you have 3 quarters, 5 dimes, and 2 nickels in your

pocket, what is the probability that you will reach into your
pocket and choose a coin, keep it in your hand, then reach
in to choose another coin and both coins will be quarters?

Answer 1

1/15

Explanation:

The two events are not dependent so we can not use multiplication rule.

So P(getting a quarter on the first try) is

`(3)/(10)`

Assuming we get a quarter, we would be left with 9 coins, and only 2 quarters, so

P(getting a quarter second time in a row)

`(2)/(9)`

Multiply the two

`(3)/(10) * (2)/(9) = (6)/(90) = (1)/(15)`