A volunteer ambulance service handles 0 to 5 service calls on any given day. The probability distribution for the number of service calls is shown below. NUMBER OF SERVICE CALLS PROBABILITY 0 .10 1 .15 2 .30 3 .20 4 .15 5 .10 a) What is the expected value or mean number of service calls?
b) What is the variance and standard deviation of the service calls?