8. A manufacturer produces a special alloy steel with an average tensile strength of 26,000 psi. A change in the composition of the alloy is said to increase the breaking strength but not affect the standard deviation which is known to be 400 psi. The manufacturer wants to conclude that the tensile strength has increased only if he is 99% sure of this (c = 0.01). If the average tensile strength is increased by as much as 300 psi, the manufacturer wants to err by not detecting the change at most 10% of the time (β = 0. 10). Assume that the z statistic with respect to the type I error is 2.33 and the z statistic with respect to the typeⅡerror is -1.28. The required sample size to meet these conditions is___________.