Testing difference between two population means.
An axial load of an aluminium can is the maximum weight that the sides can support before collapsing. The axial load is an important measure, because the top lids are pressed onto the sides with pressures that differ between 158lb and 165lb. Pepsi experimented with thinner aluminium cans, and a random sample of 175 of the thinner cans has a mean axial load of 267.11lb. The standard cans have a mean axial load of 281.81 lb and the standard deviation of 27.77 lb. Use a 0.01 significance level to test the claim that the thinner cans have a mean axial load that is less than 281.81 lb. Suppose that o=27.77 lb. Do the thinner cans appear to be strong sufficient so that they are not crushed when the top lids are pressed onto the sides?