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 or both.

Explanation

To solve the problem step by step, we will use the principle of probability and the formula for the probability of the union of two events.

### Step-by-Step Solution:

1. **Identify the given probabilities:**
- Let \( P(A) \) be the probability that a student studies Mathematics. According to the problem, \( P(A) = 40\% = \frac{40}{100} = \frac{4}{10} \).
- Let \( P(B) \) be the probability that a student studies Biology. According to the problem, \( P(B) = 30\% = \frac{30}{100} = \frac{3}{10} \).
- Let \( P(A \cap B) \) be the probability that a student studies both Mathematics and Biology. According to the problem, \( P(A \cap B) = 10\% = \frac{10}{100} = \frac{1}{10} \).
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