1.The compressive strength of concrete has a (population) mean of 2500 psi and a (population) standard deviation of 50 psi. Find the probability that a random sample of n= 5 specimens will have a sample mean strength that falls in the interval from 2490 psi and 2510 psi.
2.Determine the dimensions of the best hydraulic trapezoidal concrete channel section to convey water at a rate of 2200 gal per min on a channel slope of 0.015 m/m.