Do the computations in Prob. 4 without the use of the DeMoivre–Laplace limit theorem.

Data from Prob. 4

Does a process of producing stainless steel pipes of length 20 ft for nuclear reactors need adjustment if, in a sample, 4 pipes have the exact length and 15 are shorter and 3 longer than 20 ft? Use the normal approximation of the binomial distribution.