3. According to an IRS study, it takes a mean time of 290 minutes for taxpayers to prepare, copy and electronically transfer a 1040 tax form. The standard deviation of this distribution is 75 minutes. A consumer watchdog agency selects a random sample of 45 taxpayers for further study.
A. What is the shape, mean(expected value), and standard deviation of the sampling distribution of the sample mean for samples of size 45?
B. What is the probability that the sample mean is greater than 310 minutes?
C. What is the probability that the sample mean is less than 5 hours?
4. An airline wants to estimate the average number of unoccupied seats per flight. A random sample of 30 flights is selected and the mean number of unoccupied seats is 7.6. Assume that the population standard deviation of unoccupied seats is known to be 3.9. Compute and explain a 95% confidence interval estimate of the population mean number of unoccupied seats per flight.
5. Two percent (.02) of the items produced by a machine are defective. A random sample of 55 items is selected and checked for defects. Use the normal approximation to the binomial to find:
A) the probability that the sample will contain 4 or more defects?