Question

A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 753 hours. A random sample of 20 light bulbs has a mean life of 732 hours. Assume the population is normally distributed and the population standard deviation is 61 hours. At a =0.02, do you have enough evidence to reject the manufacturer's claim? Complete parts (a) through (o). (a) Identify the null hypothesis and alternative hypothesis. O A. Ho: < 732 (claim) H: 2732 OD. Ho: S732 H:> 732 (claim) (b) Identify the critical value(s). Use technology OB. Ho:# 753(claim) H: "753 O E. How > 753 Hus 753 (claim) OC. Hou - 732 Hu*732(claim) OF. Ho: 2753 (claim) M: <753 (Use a comma to separate answers as needed. Round to two decimal places as needed.)

Answer 1

Solution :

This is the left tailed test .

Ε Η: με 753 (claim) H, μ<753

$\alpha$ = 0.02

(b)

Z _0.02 = -2.05

Critical value = -2.05