Question 8(1 point) Efficiency experts study the processes used to manufacture i

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Question 8(1 point) Efficiency experts study the processes used to manufacture items in order to make them as efficient as possible. One of the steps used to manufacture a metal clamp involves the driling of three holes. In a sample of 72 clamps, the mean time to complete this step was 43.0 seconds. Assume that the population standard deviation is 12 seconds. what is the lower bound of the 98% confidence interval? Round your answer to one decimal place (for example: 41.9). Write only a number as your answer. Your Answer Answer Save Question 9 (1 point) A college admissions officer takes a simple random sample of 92 entering freshmen and computes their mean mathematics SAT score to be 439. Assume the population standard deviation is 12, what is the lower bound of the 99% confidence interval? Round your answer to the nearest inteper Write only a number as your answer Your Answer:

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8. The lower bound is to be given by:

Mean - Z*Stdev/sqrt(N)

= 43 - Z*12/sqrt(72)

Lets go to the Z tables and get Z for 98% CI. It is 2.33

So, The lower bound is : 43-2.33*12/sqrt(72) = 39.705

9. The 99% bound has a Z score of 2.575 ( we have used Z tables to get this)

The bound' formulae is Mean +/- Z*Stdev/sqrt(N)

= 439 +/- 2.575*124/sqrt(92)

= 405.711 to 472.289

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