A jar contains 2 pennies, 6 nickels and 4 dimes. A child selects 2 coins at random without replacement from the jar. Let X represent the amount in cents of the selected coins.

Question

a. Find the probability X = 11.
b. Find the expected value of X

Answer 1

If x = 11 for two coins, they must be a penny and a dime.

P(dime) = 4/12

P(penny) = 2/11 because one coin already removed from jar.

X = 4/12 *2/11 = ?

Answer 2

A jar contains 7 pennies, 7 nickels and 4 dimes. A child selects 2 coins at random without replacement from the jar. Let X represent the amount in cents of the selected coins.