A light bulb manufacturer guarantees that the mean life of a certain type of lig

Question

A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 737 hours. A random sample of 22 light bulbs has a mean life of 715 hours. Assume the population is normally distributed and the population standard deviation is 61 hours. At a = 0.05, do you have enough evidence to reject the manufacture's claim? Compute parts (a) through (e). (a) Identify the null hypothesis and alternative hypothesis. A. H_0: mu lessthanorequalto 715 H_a: mu > 715 (claim) B. H_0: mu > 737 H_a: mu lessthanorequalto 737 (claim) C. H_0: mu = 715 H_a: mu notequalto 715 (claim) D. H_0: mu

Explanation / Answer

here option F is right

here std error =std deviation/(n)1/2 =61/(22)1/2 =13.005

hence test stat z=(715-737)/13.005= -1.6916

for above p value=0.0454

as p value is less then 0.05 level we reject null hypothesis and conclude that mean life is less then 737

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