The Rockwell hardness of a metal is determined by impressing a hardened point into the surface of the metal then measuring the depth of penetration of the point. Suppose the Rockwell hardness of a particular alloy is normally distributed with mean 70 and standard deviation 3 (assume the Rockwell hardness is measured on a continuous scale) a) If a specimen is acceptable only if its hardness is between 67 and 75, what is the probability that a randomly chosen specimen has an acceptable hardness