Mean deviation about mean is a measure of dispersion that indicates the average distance of observations from the mean. It is also known as the mean absolute deviation.

To calculate mean deviation about mean for the given distribution, follow these steps:

Step 1: Find the mean of the distribution
- Sum up the products of each observation and its frequency:
5x3 + 10x4 + 15x6 + 20x5 + 25x3 + 30x2 = 395
- Divide the sum by the total frequency:
395 / 23 = 17.17 (rounded to two decimal places)
- Hence, the mean of the distribution is 17.17.

Step 2: Find the deviation of each observation from the mean
- Subtract the mean from each observation:
5-17.17 = -12.17
10-17.17 = -7.17
15-17.17 = -2.17
20-17.17 = 2.83
25-17.17 = 7.83
30-17.17 = 12.83

Step 3: Find the absolute deviation of each observation from the mean
- Take the absolute value of each deviation:
|-12.17| = 12.17
|-7.17| = 7.17
|-2.17| = 2.17
|2.83| = 2.83
|7.83| = 7.83
|12.83| = 12.83

Step 4: Find the sum of absolute deviations
- Sum up the absolute deviations:
12.17 + 7.17 + 2.17 + 2.83 + 7.83 + 12.83 = 44

Step 5: Find the mean deviation about mean
- Divide the sum of absolute deviations by the total frequency:
44 / 23 = 1.91 (rounded to two decimal places)
- Hence, the mean deviation about mean for the given distribution is 1.91.

In summary, the mean deviation about mean for the given distribution is 1.91. This indicates that on average, observations deviate from the mean by 1.91 units.