Question

4.         A city park employee would like to determine the mean weight of an urban raccoon. To do so, they caught and weighed 25 raccoons (this constitutes a random sample) and recorded the weight of each. The mean of this sample was found to be 22.3 pounds and the standard deviation of this sample was 8.4 pounds. Assume raccoon weights are normally distributed.

            Determine the 90% confidence interval for the mean weight of an urban raccoon.

Then complete the sentence provided below:

With 90% confidence the mean weight of a racoon is between ______________ lbs and _______________ lbs .

Answer 1

4)

Solution :

t _/2,df = 1.711

Margin of error = E = t_/2,df * (s /n)

= 1.711 * (8.4 / 25)

Margin of error = E = 2.9

The 90% confidence interval estimate of the population mean is,

- E < < + E

22.3 - 2.9 < < 22.3 + 2.9

19.4 < < 25.2

With 90% confidence the mean weight of a racoon is between 19.4 lbs and 25.2 lbs .