A box contains one each of $1, $10, $20, $50, and $100 bills. It costs $30 to reach in and withdraw one bill. What is the expected value?
A) $5.50
B) $7.60
C) $6.20
D) $4.80
E) $6.90

Question

Quizplus · Accepted Answer

There are five bills in the box, so each bill has a probability of $\frac{1}{5}$ of being selected. The expected value is the sum of the products of the value of each bill and its probability of being selected. Thus, the expected value is $$\frac{1}{5}(\$1)+\frac{1}{5}(\$10)+\frac{1}{5}(\$20)+\frac{1}{5}(\$50)+\frac{1}{5}(\$100)=$$ $$\$6.20$$ Therefore, the best choice is $\boxed{	extbf{(C)}}.$

A Box Contains One Each of $1, $10, $20, $50