The president of Doerman Distributors, Inc., believes that 26% of the firm's orders come from first-time customers. A simple random sample of 80 orders will be used to estimate the proportion of first-time customers.

A simple random sample of five months of sales data provided the following information:

1. Develop a point estimate of the population mean number of units sold per month.
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2. Develop a point estimate of the population standard deviation (to 2 decimals).
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The College Board American College Testing Program reported a population mean SAT score of = 1020 (The World Almanac 2003). Assume that the population standard deviation is = 100.

1. What is the probability that a random sample of 75 students will provide a sample mean SAT score within 10 of the population mean (to 4 decimals)?
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2. What is the probability a random sample of 75 students will provide a sample mean SAT score within 20 of the population mean (to 4 decimals)?
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