An instructor allows students to take an exam as many times as needed until the student obtains a passing grade. The following is a record of the number of students in a class of 20 who took the test and the number of tests taken in order to obtain a passing grade.
|
Students
|
Number of Tests
|
|
9
|
1
|
|
6
|
2
|
|
3
|
3
|
|
2
|
4
|
1. Use the relative frequency approach to construct a probability distribution and show that it satisfies the required condition.
2. Find the expected value of the number of tests taken.
3. Compute the variance.
4. Compute the standard deviation.