Question 1:

The growing seasons for a random sample of 35 U.S. cities were recorded, yielding a sample mean of 190.7 days and the population standard deviation of 54.2 days. Estimate the true mean population of the growing season with 95% confidence.

[05 Marks]

Question 2:

Find the 90% confidence interval for the variance and standard deviation for the lifetimes of inexpensive wrist watches if a sample of 24 watches has a standard deviation of 4.8 months. Assume the variable is normally distributed. Do you feel that the lifetimes are relatively consistent?[05 Marks]