Explanation:

To find the mean of the distribution, we need to use the midpoint for each class interval and multiply by the frequency. Here's the calculation:

- Class 40 - 50: Midpoint = 45, Frequency = 4, Contribution = 45 * 4 = 180

- Class 50 - 60: Midpoint = 55, Frequency = 3, Contribution = 55 * 3 = 165

- Class 60 - 70: Midpoint = 65, Frequency = 1, Contribution = 65 * 1 = 65

- Class 70 - 80: Midpoint = 75, Frequency = 2, Contribution = 75 * 2 = 150

- Add all contributions: 180 + 165 + 65 + 150 = 560

- Total Frequency: 4 + 3 + 1 + 2 = 10

- Mean = Total Contributions / Total Frequency = 560 / 10 = 56

- Option 1: 51 – Incorrect

- Option 2: 52 – Incorrect

- Option 3: 54 – Incorrect

- Option 4: 56 – Correct