The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the population of checkout times is one minute. The 95% confidence interval for the true average checkout time (in minutes) is 1.00 to 5.00 2.804 to 3.196 1.36 to 4.64 3.00 to 5.00
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The standard error is the standard deviation divided by the square root of the sample size. In this case, the standard deviation is 1 minute and the sample size is 100, so the standard error is 1/√100 = 0.1 minute. Show more…
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The manager of a grocery store selected a random sample of 100 customers to estimate the average checkout time. The 90% confidence interval estimate for the average checkout time at the store is [1, 5] minutes. The correct confidence interval interpretation is We estimate with 95% probability that the average checkout time at the store is between 1 and 5 minutes. We estimate with 95% confidence that the average checkout time for the sample of 100 customers is between 1 and 5 minutes. If random samples of 100 customers are repeatedly selected, then that the average checkout time will be between 1 and 5 minutes for 95% of the samples. 100.0 to 200.0 None of these alternatives is correct.
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