A testing engineer in a light bulb factory is planning a study to estimate the average life of a large shipment of light bulbs. The engineer wants to estimate the average life within plus or minus 16 hours with 95 percent confidence. Assuming a process standard deviation of 90 hours, determine the sample size for this study.

a. 7
b. 43
c. 58
d. 122

d. 122

Step-by-step explanation:

Formula to find sample size : , where = prior population standard deviation, z= Critical z-value for confidence level and E = Margin of error.

As per given ,

Also , for 95% confidence level , z-value = 1.96

Now , Required sample size would be

Hence, the required sample size =122

Thus , the correct option is d. 122.

1/3 + 1/5 = 8/15.

step-by-step explanation:

hope it

answer: no, but if it does it's a obvious pattern.

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