1) Suppose that a standard deviation is known to be 3. How large a sample size is needed to have an error of 2 on a 99% confidence interval?
2) If n= 48 packages are randomly selected from packages received by parcel service. The sample has a mean weight of 18.6 lbs. Assume that s=3.4 lbs. What is the 95% confidence interval for the true mean weight of all packages received by the parcel service?
a) 17.8-19.4 lbs
b) 17.6-19.6 lbs
c) 17.3-19.9 lbs
d) 17.5-19.7 lbs
3) A random sample of 150 visitors to a park spent an average of $142 with a standard deviation of $47.50. Determine the 98% confidence interval for the mean money spent by all visitors to the park.
4) A marketing survey reveals that 58 out of 750 randomly selected shoppers is an extreme couponer. Find a 95% confidence interval for the population proportion of extreme couponers.
5) A random sample of n= 40 farming regions was selected to receive an average price of $9.75 with a standard deviation of $1.85 per 100 lbs of watermelon. Find a 90% confidence interval for the population mean price per 100 lbs of watermelon.