1. 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. Assume that the president is correct and p = 0.26. What is the sampling distribution of for this study?
b. Select your answer -A normal distribution because np and n(1-p) are both greater than 5A normal distribution because np and n(1-p) are both less than 5A non normal distribution What is the probability that the sample proportion will be between .20 and .40 (to 4 decimals)?
c. What is the probability that the sample proportion will be between .25 and .35 (to 4 decimals)?
2. A simple random sample of five months of sales data provided the following information:
a. Develop a point estimate of the population mean number of units sold per month.
b. Develop a point estimate of the population standard deviation (to 2 decimals).
3. 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.
a. 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)?
b. 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)?