Refer to the previous exercise. a.? ?What is the expected number of calls among the 25 that involve a fax message? b. ?What is the standard deviation of the number among the 25 calls that involve a fax message? c. ?What is the probability that the number of calls among the 25 that involve a fax transmission exceeds the expected number by more than 2 standard deviations?

Answer: Step1: Refer to the previous exercise. Given, a particular telephone number is used to receive both voice calls and fax messages. Suppose that 25% of the incoming calls involve fax messages, and consider a sample of 25 incoming calls. Here, n = 25 and p = 25% = 0.25 Step2: a). The aim is to find the expected number of calls among the 25 that involve a fax message. The expectation of ‘x’ is E(x) = x np = 25×0.25 = 6.25 Therefore,the expected number of calls among the 25 that involve a fax message is 6.25. Step3: b). Here the aim is to find the standard deviation of the number among the...