Can someone help please?

Suppose that a customer service center claims that the telephone calls it receives last 112 seconds on average, with a standard deviation of 9 seconds. If you took a sample of 324 telephone calls, which of the following mean times would be within the 95% confidence interval?

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Question

Can someone help please?

Suppose that a customer service center claims that the telephone calls it receives last 112 seconds on average, with a standard deviation of 9 seconds. If you took a sample of 324 telephone calls, which of the following mean times would be within the 95% confidence interval?

Pic below

anonymous · Answer

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ltrout · Answer

I don't really understand how to even do this problem, but here is an older post on the same problem and he walks through how to do it. http://openstudy.com/updates/53c99c39e4b0bff525b1571e

anonymous · Answer

@sithsandgiggles can you help me lol

ltrout · Answer

Do you understand the equation to solve it?