A statistics teacher claims that, on the average, 20% of her students get a grade of A, 35% get a B, 25%

get a C, 10% get a D, and 10% get an F. The grades of a random sample of 100 students were recorded. The following table presents the results.

a. How many of the students in the sample got an A? How many got an F?

b. Compute the expected frequencies.

c. Which grades were given more often than expected?
Which grades were given less often than expected?

d. What is the value of X2?

e. How many degrees of freedom are there?

f. Test the hypothesis that the grades follow the distribution claimed by the teacher. Use the 0.05 level of significance.

Transcribed Image Text:

Grade A B C D F Observed 29 42 20 5 4