Question 4 The time, T, a customer waits for his/her order follows a normal distribution with a mean of 5 minutes and standard deviation of 1.5 minutes. (Round all percentages to 1 decimal place, e.g. 37.2%) a) What percentage of customers will wait less than 4 minutes? b) Customers get impatient if they wait more than 7 minutes. What percentage of customers will be impatient? c) Suri decides to give a free ice cream to the 5% of people who wait the longest to be served. What customer wait time (to the nearest second) marks the cut-off for receiving a free ice cream? d) Suri wants to improve the wait times. Her aim is that no more than 10% of customers wait longer than 6 minutes. If the standard deviation of the waiting time remains at 1.5 minutes, what will of the average (mean) wait time have to be, in order for her aim to be met? Show all steps of working and give your answer to the nearest second. 8