1. A recent report stated that 15% (0.15) of all men in the U.S. are left-handed. A random sample of 250 men is selected to further study this question.
A. What is the Shape, Mean (expected value) and standard deviation of the sampling distribution of the sample proportion for samples of size 250?
B. What is the probability that the sample proportion for a sample of size 250 is greater than 10% (0.10)?
C. What is the probability that the sample proportion for a sample of size 250 is between 12% (0.12) and 18% (0.18)?
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2. To study water usage in a town, a Manager selected a random sample of 22 households and found a sample mean usage of 346.2 gallons of water per day with a sample standard deviation of 50.5 gallons. Compute and explain a 95% confidence interval estimate of the population mean water usage per day.
3. What is the minimum sample size needed to estimate the population mean salary of a company at 95% confidence with a margin of error of $1,500? Assume that the population standard deviation is known to be $6,500.