The pitney pipe company is one of several large domestic manufacturers of pvc pipe. the quality control department sampled 600 10-foot lengths. at a point 1 foot from the end of the pipe, they measured the outside diameter. the mean was 14 incles and the standard deviation was 0.1 inches. if we assume that the distribution of diameters is symmetrical and bell-shaped, about 95% of the observations will be between what two values?