Question

From a set of 5 nickels, 10 dimes and 15 quarters, six coins are removed at random without replacement.

a. Find the probability of not removing 6 quarters.
b. Find the probability of removing exactly 2 nickels, 2 dimes and 2 quarters.

Answer 1

(a) 1 - (15 C 6) / (30 C 6)

(b) (5 C 2) x (10 C 2) x (15 C 2) / (30 C 2)

Explanation:

Number of nickels = 5

Number of dimes = 10

Number of quarters = 15

(a) The probability of getting 6 quarters

= (15 C 6) / (30 C 6)

So, the probability of not getting 6 quarters = 1 - (15 C 6) / (30 C 6)

(b) Probability of getting 2 nickels , 2 dimes and 2 quarters

= (5 C 2) x (10 C 2) x (15 C 2) / (30 C 2)