Good-Buy Electronics: You own a branch of Good-Buy Electronics and have been tol

Question

Good-Buy Electronics: You own a branch of Good-Buy Electronics and have been told by the manufacturer of Stevuski Televisions that only 5% of their brand of TVs die within one year. Last year, your branch sold 128 such televisions in July. One year later, 14 (about 11%) of them had been returned — dead.

(a) Assuming the 5% value quoted by the manufacturer was accurate, what is the mean number of TVs that die within one year in randomly samples of size 128? Round your answer to one decimal place. =

(b) What is the standard deviation? Round your answer to one decimal place. =

(c) You had 14 TVs die out of 128 (about 11%). With respect to the mean and standard deviation found in parts (a) & (b) respectively, what is the z-score for this many dead TVs? Round your answer to two decimal places. z =

Explanation / Answer

(a) Assuming the 5% value quoted by the manufacturer was accurate, what is the mean number of TVs that die within one year in randomly samples of size 128? Round your answer to one decimal place.

Answer : = Number of Tvs * proportion TVs dies =128 * 0.05 = 6.4 TVs

(b) What is the standard deviation? Round your answer to one decimal place.

= Sqrt [ p(1-p) * N] = sqrt [ 0.05 * 0.95 * 128] = 2.466 Tvs

(c) You had 14 TVs die out of 128 (about 11%). With respect to the mean and standard deviation found in parts (a) & (b) respectively, what is the z-score for this many dead TVs? Round your answer to two decimal places.

z = (x- )/ = (14 - 6.4)/ 2.466 = 3.08

respective p - value = 0.001

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