# 11.4.1. Calculating Probability

If the success probability of a student in physics is 0.85, in mathematics is 0.8, and in both subjects is 0.71, find his success probability in at least one of the two subjects.

- A0.94
- B0.14
- C0.09
- D0.85

### Example

If the success probability of a student in physics is 0.85, in mathematics is 0.8, and in both subjects is 0.71, find his success probability in at least one of the two subjects.

### Solution

In this case, event

In other words, the notation

Thus, the probability of the student's success in at least one of the two subjects is 0.94.