An appliance repair company that makes service calls to customers’ homes has found that 5% of the time there is nothing wrong with the appliance and the problem is due to customer error (appliance unplugged, controls improperly set, etc.). Two service calls are selected at random, and it is observed whether or not the problem is due to customer error. Draw a tree diagram. Find the probability that in this sample of two service calls
a. Both problems are due to customer error
b. At least one problem is not due to customer error