Calculate the mean and standard deviation for the following distribution: Marks:, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90 No. of students:, 3, 6, 13, 15, 14, 5, 4

Explanation

To calculate the mean and standard deviation for the given distribution of marks, we will follow these steps:

### Step 1: Create a Frequency Table
We will create a table with the class intervals, their mid-values, frequencies, and necessary calculations.

| Class Interval | Mid-value (X_i) | Frequency (f_i) |
|----------------|------------------|-----------------|
| 20 - 30 | 25 | 3 |
...