A professor has noticed that, even though attendance is not a component of the final grade for the class, students that attend regularly generally get better grades. In fact, 39% of those who come to class on a regular basis receive A's. Only 14% who do not attend regularly get A's. The long run attendance rate is 81%. Based on this class profile find the following:

Question

A professor has noticed that, even though attendance is not a component of the final grade for the class, students that attend regularly generally get better grades. In fact, 39% of those who come to class on a regular basis receive A's. Only 14% who do not attend regularly get A's. The long run attendance rate is 81%. Based on this class profile find the following:

Hint: pretend that there are 1000 students in the class and use the values given in the problem to construct the appropriate contingency table. Round cell frequencies to the nearest integer
1) The percent who attend class regularly given that they get A's____

2) The odds that a person who attends regularly gets an "A" in the class___

3) The odds ratio of getting an A in the class for those attend regularly versus those who do not attend____

Answer 1

I think you need to provide more information. Or you need to make some strong assumptions about how often a "not regular" attends (e.g., 50% of the time??)

Answer 2

Though I'm not 100%, I'm fairly certain you're in my class. This being said, anyone who reads this and intends to help, please understand that this information IS all that we have to work with.

Answer 3

1. 39

2. 47
3. 33

Answer 4

To answer these questions, we need to construct a contingency table based on the given information and then use the table to calculate the required percentages and odds.

Step 1: Construct the contingency table:
We know that there are 1000 students in the class. Let's create a contingency table with rows representing attendance (Regular or Irregular) and columns representing grades (A or Not A).

| A | Not A | Totals |
Regular | | | |
Irregular| | | |
Totals | | | 1000 |

The table is currently empty, so we'll need to fill it in using the given information.

Step 2: Fill in the contingency table:
Based on the problem, we know that the long-run attendance rate is 81%. This means 81% of 1000 students attend class regularly, which is equal to 810 students. Therefore, in the table we can fill the regular attendance row with a total of 810 students and the irregular attendance row with the remaining 190 students.

| A | Not A | Totals |
Regular | | | 810 |
Irregular| | | 190 |
Totals | | | 1000 |

Now, let's fill in the grade distribution. We're given that 39% of those who attend class regularly receive A's. So, 39% of 810 students would be approximately 316 students (0.39 * 810 = 315.9, rounded to 316). The remaining 494 students (810 - 316 = 494) in the regular attendance row would receive "Not A" grades.

| A | Not A | Totals |
Regular | 316 | 494 | 810 |
Irregular| | | 190 |
Totals | | | 1000 |

We also know that only 14% of those who do not attend regularly receive A's. This represents 14% of 190 students, which is approximately 27 students (0.14 * 190 = 26.6, rounded to 27). Hence, the remaining 163 students (190 - 27 = 163) in the irregular attendance row would receive "Not A" grades.

| A | Not A | Totals |
Regular | 316 | 494 | 810 |
Irregular| 27 | 163 | 190 |
Totals | | | 1000 |

Step 3: Calculate the required percentages and odds:

1) The percent who attend class regularly given that they get A's:
To find this percentage, we divide the number of students who attended regularly and got A's (316) by the total number of students who got A's (316 + 27 = 343) and then multiply by 100.

Percent who attend class regularly given that they get A's = (316 / 343) * 100 ≈ 92.11%

2) The odds that a person who attends regularly gets an "A" in the class:
The odds can be calculated by dividing the number of regular attendees who got A's (316) by the number of regular attendees who didn't get A's (494).

Odds = 316 / 494 ≈ 0.639

3) The odds ratio of getting an A in the class for those who attend regularly versus those who do not attend:
The odds ratio can be calculated by dividing the odds of getting an A for regular attendees (316/494) by the odds of getting an A for irregular attendees (27/163).

Odds ratio = (316/494) / (27/163) ≈ 3.02

So, the required answers are:
1) The percent who attend class regularly given that they get A's ≈ 92.11%
2) The odds that a person who attends regularly gets an "A" in the class ≈ 0.639
3) The odds ratio of getting an A in the class for those who attend regularly versus those who do not attend ≈ 3.02