Calculate the mean and standard deviation for the following table given the age distribution of a group of people: Age: 20-30 30-40 40-50 50-60 60-70 70-80 80-90 No. of persons: 3 51 122 141 130 51 2

Explanation

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

### Step 1: Create a Frequency Table
We will create a table with the age intervals, the midpoint of each interval (xi), the frequency (fi), and calculate the necessary values.

| Age Interval | Midpoint (xi) | Frequency (fi) |
|--------------|---------------|----------------|
| 20 - 30 | 25 | 3 |
...