The proportion of defective telephones manufactured on Mondays is 0.3. If a sample of 20 telephones is selected, what is the probability that 5 of the phones in the sample are defective? Use the normal distribution to approximate the binomial. Since this is a continuous distribution approximating a discrete distribution, use X values of 4.5 and 5.5. Show your work.
μ = np and σ = √ npq
Using normal approximation we have
μ = np = 20*0.3 = 6
σ = √ npq ...