When an opinion poll selects cell phone numbers at random to dial, the cell phone exchange is first selected and then random digits are added to form complete telephone number: When using this procedure to generate random cell phone numbers approximately 55% of the cell numbers generated correspond to working numbers. You watch a pollster dial 15 cell numbers that have been selected in this manner:What is the mean number of calls that reach a working cell number? 8.25300.55 0 15