Question

PLEASE SHOW ALL WORK AND EXPLAIN

To test that the mean lifetime of light bulbs is at least 845 hours (population is normally distributed and

population standard deviation is 25), a random sample of 36 bulbs is tested, yielding a sample mean of

850 hours. What conclusion would you reach if alpha = .04? Show all steps of hypothesis testing. You

must state your conclusion in terms of the context of the mean lifetime of light bulbs.

Answer 1

H0: Null Hypothesis: 845 (Claim)

HA: Alternative Hypothesis: 845

SE = /

= 25/= 4.1667

Test statistic is given by:
Z = (850 - 845)/4.1667 = 1.20

= 0.04

One Tail - Left Side Test

From Table, critical value of Z = - 1.75

Since calculated value of Z = 1.20 is greater than critical value of Z = - 1.75, the difference is not significant. Fail to reject null hypothesis.

Conclusion:
The data support the claim that the mean life of light bulbs is at least 845 hours.