Question: Repair calls. Find the mean and standard deviation of the number of repair calls the appliance shop in Exercise should expect during an 8-hour day.
Exercise: Repairs. The probability model below describes the number of repair calls that an appliance repair shop may receive during an hour.
Repair Calls 0 1 2 3
Probability 0.1 0.3 0.4 0.2
a) How many calls should the shop expect per hour?
b) What is the standard deviation?