Question

A piggy bank contains 4 quarters, 18 dimes, 10 nickels, and 8 pennies. A coin is chosen at random, not replaced, then another is chosen. Find each probability. P(worth at least 10 cents, then penny)

Answer 1

The probability of choosing a coin that is worth at leas 10 cents is:

$P=\frac{22}{40}=\frac{11}{20}$

then the probability of obtaining a penny is:

$P=\frac{8}{39}$

Then the probability to obtain a coin of at least 10 cents and then a penny is:

$P=\frac{11}{20}\cdot\frac{8}{39}=\frac{22}{195}$