The manager of a medical centre is concerned that some patients have to stand for long periods of time while the receptionist processes their appointment details. His goal is that the receptionist should spend no more than one minute with each patient. He requests your help in conducting a statistical analysis of the situation to see what adjustments will need to be met in order to meet this goal

(i) If random samples of 40 patients were selected, what proportion of the sample means would be between 90 and 150 seconds?