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 729 hours. A random sample of 24 light bulbs has a mean life of 703 hours. Assume the population is normally distributed and the population standard deviation is 59 hours. At ?=0.08, do you have enough evidence to reject the manufacturer's claim? Complete parts (a) through (e). (a) Identify the null hypothesis and alternative hypothesis A. Ho H-703 B Hs 703 C. H:>729 Ha: ? Ho : ? 703 (claim) 729 (claim) O D. Ho H 2 729 (claim) E. Ho : #729(claim) F. Ha H729 Ha H729 (b) Identify the critical value(s). Use technology (Use a comma to separate answers as needed. Round to two decimal places as needed.) ldentify the rejection region(s). Choose the correct answer below B. O C. Fail to reject Ho Fail to reject Ho Fail to reject H Reject Ho Reject Ho Reject Ho Reject Ho

Explanation / Answer

Ans:

a)Option D is correct.(left tailed test)

b)critical z value(left tailed)=normsinv(0.08)=-1.41

Option B is correct.(reject H0,if z<-1.41)

c)

Test statistic:

z=(703-729)/(59/sqrt(24))

z=-2.16

d)As,z=-2.16<-1.41,we reject null hypothesis(H0).

There is sufficient evidence to reject the claim that mean bulb life is atleast 729.

Option C is correct.

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