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

### Step 1: Define the probabilities
Let:
- \( P(M) \) = Probability that a student studies Mathematics = 40% = \( \frac{40}{100} = \frac{2}{5} \)
- \( P(B) \) = Probability that a student studies Biology = 30% = \( \frac{30}{100} = \frac{3}{10} \)
- \( P(M \cap B) \) = Probability that a student studies both Mathematics and Biology = 10% = \( \frac{10}{100} = \frac{1}{10} \)

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