+188 One-hundred students were allowed to re-take an exam for their math course. The probability distribution shows how studying for the latest exam affected their grade when compared with the first time they took the exam. What is the probability that a student who studied for the exam saw an increase in their exam grade? Round to the nearest thousandth.
| Exam Grades | Studied | Didn't Study | Totals |
| Raise in grades | 0.52 | 0.06 | 0.58 |
| No Raise in Grades | 0.05 | 0.37 | 0.42 |
| Totals | 0.57 | 0.43 | 1 |
A. 0.088
B. 0.897
C. 0.912
D. 0.570
C. 0.912
If you're interested why:
'What is the probability that a student who studied for the exam saw an increase in their exam grade?'
From the question we're only interested in students who studied so we only need to worry about the 'studied' column.
Next we need to know what percentage (probability) of students who studied saw an increase.
So we simply divide the number of students who studied and saw an increase (0.52) by the total number of students who studied (0.57).
0.52 / 0.57 = 0.912280...
