1.

A statistics professor wants to compare today's students with those 25 years ago. All of his current students' marks are stored on a computer so that he can easily determine the population mean. However, the marks 25 years ago reside only in his musty files. He does not want to retrieve all the marks and will be satisfied with a 98% confidence interval estimate of the mean mark 25 years ago. If he assumes that the population standard deviation is 13, how large a sample should he take to estimate the mean to within 4 marks?

Sample Size =

2.

(1 point) Enter your final answers correct to two decimal places.

The table below lists the body temperatures of six randomly selected subjects from each of three different age groups. Use the=0.01 significance level to test the claim that the three age-group populations have different mean body temperatures.

16-20 21-29 30 and older

subject 1 98.7 98.2 97.1

subject 2 97.4 97.9 97.3

subject 3 98.4 97.9 97.4

subject 4 98.6 98.9 97.4

subject 5 97.8 98.3 97.6

subject 6 97.3 98.5 97

Totals 588.2 589.7 583.8

Sum of sq. 57665.1 57958.41 56803.98

The test statistic isF=

The critical value isF=

Is there sufficient evidence to warrant the rejection of the claim that the three age-group populations have the same mean body temperature?

A.Yes

B.No

3.

One of the most feared predators in the ocean is the great white shark. It is known that the white shark grows to a mean length of21feet; however, one marine biologist believes that great white sharks off the Bermuda coast grow much longer. To test this claim, full-grown white sharks were captured, measured, and then set free. However, this was a difficult, costly and very dangerous task, so only four sharks were actually sampled. Their lengths were 20,24,25,and24feet. Do the data provide sufficient evidence to support the claim? Use =0.01and the fact thats=2.21735578260835

(a) Calculate the test statistic: t =

(b) Find the critical value: t* =

(c) The final conclusion is

A.We can reject the null hypothesis that the average length of the shark is21

B.There is not sufficient evidence to reject the null hypothesis that the average length of the shark is21