Question

5. The height of pine trees is known to be a normal random variable with a standard deviation of 10 feet A forester wants to have a 98% confidence interval for the mean height, but with a margin of error not exceeding +3 feet. How many trees does he need to measure? A metallurgist wanted to estimate the mean weight of silver ingots. The following weights (in pounds) were measured: 6. 40.2, 43.1, 45.5, 44.5, 39.5, 40.2, 41.0, 41.6, 43.1, 44.9 (a) What assumption needs to be made in order to calculate a confidence interval for the mean? (b) Find the 90% confidence interval for the mean length.

Answer 1