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StatisticsQ&A LibrarySam is the manager of a used clothing store. He wants to estimate the average amount a customer spends per visit. A random sample of 70 customers’ receipts gave a mean of = $7.10 with a standard deviation s = $2.30. Find a 99% confidence interval for the average amount spent by all customers. Interpret your findings.Question

Asked Mar 25, 2020

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Sam is the manager of a used clothing store. He wants to estimate the average amount a customer spends per visit. A random sample of 70 customers’ receipts gave a mean of = $7.10 with a standard deviation s = $2.30. Find a 99% confidence interval for the average amount spent by all customers. Interpret your findings.

Step 1

From the provided information,

The population standard deviation is not known therefore *t* distribution will be used to obtain the confidence interval.

The degree of freedom = *n* – 1 = 70 – 1 = 69

99% confidence level means *α* = 1 – 0.99 = 0.01

The critical value of *t* at 0.01 level of significance with 69 degre...

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