In Class XI of a school 40% of the students study Mathematics and 30% study Biology. 10% of the class study both Mathematics and Biology. If a student is selected at random from the class, find the probability that he will be studying Mathematics or Biology.

Explanation

To solve the problem, we need to find the probability that a randomly selected student from the class is studying either Mathematics or Biology. We can use the formula for the probability of the union of two events.

### Step-by-Step Solution:

1. **Define the Variables**:
Let \( x \) be the total number of students in the class.

2. **Calculate the Number of Students Studying Mathematics**:
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