Die operasionele bestuurder van ʼn suikermeul in Durban wil die gemiddelde grootte van bestellings beraam. Die grootte van ʼn bestelling word gemeet in aantal palette verskeep. ʼn Ewekansige steekproef van 87 bestellings van klante het ʼn steekproefgemiddeld van 131.6 palette. Aanvaar dat die populasiestandaardafwyking 25 palette is en dat die bestellinggroottes normaal verdeel is. Die 90% vertrouensinterval vir die populasie gemiddelde bestellingsgrootte van alle klante is / The operations manager of a sugar mill in Durban wants to estimate the average size of an order received. The size of an order is measured in the number of palettes shipped. A random sample of 87 orders from customers had a sample mean value of 131.6 palettes. Assume that the population standard deviation is 25 palettes and that the order size is normally distributed. The 90% confidence interval for the population mean order size received from all customers is