We wish to determine how much taller, on average, male university students are than female university students. A random sample of 15 male students and a random sample of 20 female students was selected. The height of each student was recorded and a summary of the data is given below.

a)

Construct a confidence interval for the mean difference in height between the men and woman.

b)

Test whether the men are, on average, more than 4 inches taller than the women.

During the term Dr. Field conducted an experiment on choosing the most influential individuals over the last millennium. The number of scientists chosen by each student was recorded as well as the student's majpr field of study. A summary of the data is given below.

Is there any evidence in this data that science students are more likely to choose scientists than non-science students?

a)

Display the data. Do the science students appear to choose more scientists than the non-science students? Are the distributions of the two groups more or less symmetric? Are there any large outliers?

b)

Do the appropriate test stating null and alternative hypothesis, value of the test statistic and p-value. How strong is the evidence against the null hypothesis? For what values of would the null hypothesis be rejected? What is your conclusion?

c)

What assumptions do we need to make when doing this test? Do the assumptions seem reasonable in this case?

Fifteen of two types of fabricated wooden beams were tested for breaking load with the following results:

Find the confidence interval for the difference between mean breaking loads. Would you conclude that the means were signifacantly different (use ); ie. would you reject ?