ʼn Biostatistikus wil die gemiddelde gewigsverlies van mense op ʼn nuwe dieëtplan beraam. Uit ondervinding weet hy dat die populasie gewigsverlies ʼn standaardafwyking van 5 kilogram het. Hoe groot steekproef moet hy neem om die gemiddelde gewigsverlies binne ʼn interval van 2 kilogram te beraam met 90% vertoue? / A biostatistician wants to estimate the average weight loss of people who are on a new diet plan. He knows from past experience that the standard deviation of the population of weight losses is 5 kilograms. How large a sample should he take to estimate the mean weight loss to within an interval of 2 kilograms, with 90% confidence?