an automobile manufacturer wants to estimate the mean gasoli

an automobile manufacturer wants to estimate the mean gasoline mileage that its customers will obtain with its new compact model. how many sample runs must be performed in order that the estimate be accurate to within 0.3 mpa at 95% confidence? (assume that alpha = 1.5)

Solution

Given a=1-0.95=0.05, Z(0.025) = 1.96 (from standard normal table)

So n=(Z*s/E)^2

=(1.96*1.5/0.3)^2

=96.04

Take n=97