Answer:
$ 7.7
Step-by-step explanation:
Given,
There are 18 $1 bills, ten $5 bills, eight $10 bills, three $20 bills, and one $100 bill,
Total number of bills = 18 + 10 + 8 + 3 + 1 = 40,

Thus,
The probability of $ 1 = 
The probability of $ 5 = 
The probability of $ 10 = 
The probability of $ 20 = 
The probability of $ 100 = 
If a bill is selected randomly,
The expected value of the bill



= $ 7.7