Bob Newman owns a small computer repair shop in the Uptown area. He provides standard repair services for laptops and computers, virus removal, and data recovery. Bob is trying to grow his business and capture more customers by advertising his average service time. Based on a sample of 40 receipts, he finds that the mean service time is 2 hours and 10 minutes with a standard deviation of 30 minutes. Based on this information answer the following questions.

Part 1

What is the 90% confidence interval for mean service time (in minutes)?

Group of answer choices

1. 120.40139.60
2. 120.70139.30
3. 122.20137.80
4. 122.01137.99

Part 2 is an essay part

Interpret in words the 90% confidence interval for service time?

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Part 3

Calculate the 90% margin of error for service time (in minutes).

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Answer within two decimal places.

Part 4 is an essay question

If a larger sample size was collected, what impact would that have on the confidence interval? Would the margin of error increase or decrease and why based on statistical theory (not mathematics)? Assume the data is random.

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