I am not sure how to approach this question. initially it appears very simple, but all the other problems were incredibly difficult so I know I must be missing something. Can someone help me with this please?

The mean number of minutes each phone call lasts at a bank's customer service center is 12.5 minutes. Suppose the standard deviation is one minute. Assume a random sample of 55 phone calls is obtained. (a) What are the mean and standard deviation for the sample mean of the phone call times? [5 marks] (b) Find the 95-th percentile for the sample mean time for phone call times. Interpret this value in a complete sentence. [5 marks] (c) Find the probability that the sample mean is between 12 to 13 minutes. [5 marks]