A company provides call center services for businesses. The company bills it clients either by the call or by the minute. The company is negotiating with a new client who wants to be billed by the minute. Before a contract is written, the company plans to receive a random sample of calls and record the minutes spent on the phone in order to estimate the mean call time. It wishes to develop a 94% confidence interval estimate for the population mean call time and wants this estimate to be within :l: 0.14 minutes. The question is, how many calls should the company use in its sample? Since the population standard deviation is unknown, a pilot sample was taken by having three call centers each take 50 calls for a total pilot sample of 150 calls. The minutes for these calls are in the accompanying data table. Complete parts a and b below. Click on the icon to view the data table. a. How many additional calls will be needed to compute the desired condence interval estimate forthe population mean? At least additional calls will be needed. (Round up to the nearest whole number as needed.)