There are 60% students in Maths and 30% in Biology. If 10% students are in both subjects. Find the probability that a randomly selected student has Maths or Biology.

Explanation

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

### Step-by-Step Solution:

1. **Identify the given probabilities**:
- Probability of students in Maths, \( P(M) = 60\% = \frac{60}{100} = \frac{6}{10} \)
- Probability of students in Biology, \( P(B) = 30\% = \frac{30}{100} = \frac{3}{10} \)
- Probability of students in both subjects, \( P(M \cap B) = 10\% = \frac{10}{100} = \frac{1}{10} \)

2. **Use the formula for the probability of the union of two events**:
The formula for the probability of either event A or event B occurring is:
\[ P(M \cup B) = P(M) + P(B) - P(M \cap B) \]
where \( P(M \cup B) \) is the probability of students having either Maths or Biology.

3. **Substitute the values into the formula**:
\[ P(M \cup B) = P(M) + P(B) - P(M \cap B) \]
\[ P(M \cup B) = \frac{6}{10} + \frac{3}{10} - \frac{1}{10} \]

4. **Perform the calculations**:
\[ P(M \cup B) = \frac{6 + 3 - 1}{10} = \frac{8}{10} \]

5. **Simplify the fraction**:
\[ P(M \cup B) = \frac{8}{10} = \frac{4}{5} \]

6. **Final answer**:
The probability that a randomly selected student has either Maths or Biology is \( \frac{4}{5} \).