Question

The standard deviation of the weights of elephants is known to be approximately 15 pounds. We wish to construct a 95% confidence interval for the mean weight of newborn elephant calves. Fifty newborn elephants are weighed. The sample mean is 244 pounds. The sample standard deviation is 11 pounds.

Identify the following: x¯ = σ = n =

In words, define the random variables X and X¯.

Construct a 95% confidence interval for the population mean weight of newborn elephants. Be sure to interpret your interval clearly and in a complete sentence.

What will happen to the confidence interval obtained, if 500 newborn elephants are weighed instead of 50? Why?

Construct a 95% confidence interval for the population mean weight of newborn elephants assuming we do not have the population standard deviation but we have a sample standard deviation of Sx = 12.5lbs. Be sure to interpret your interval clearly and in a complete sentence.

Answer 1