Suppose a normal distribution has a mean of 34 and a standard deviation of two what is the probability that a data value is between 31 and 37

Aparticular 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. (a) what is the expected number of calls among the 25 that involve a fax message?