Professor Fair believes that extra time does not improve grades on exams. He randomly divided a group of 300 students into two groups and gave them all the same test. One group had exactly 1 hour in which to finish the test, and the other group could stay as long as desired. The results are shown in the following table. Test at the 0.01 level of significance that time to complete test and test results are independent.

time A. B. C. F. ROW TOTAL

1h 22. 45. 56. 13. 136

unlimited. 15. 47. 79. 23. 164

column total 37. 92. 135. 36. 300