please sketch and show work

2. A bank has kept records of the checking balances of its customers and determined that the average daily balance of its customers is $300 with a standard deviation of $48, and is a normally distributed population. A random sample of 144 checking accounts is selected. a) What is the probability that the sample mean will be less than $306.60? b) What is the probability that the sample mean will be at least $308? c) What is the probability that the sample mean will be between $302 and $310