The following is the cumulative frequency distribution (of less than type) of \(997\) persons each of age \(20\) years and above. Determine the mean age.
| Age below (in years) | Number of persons |
| \(30\) | 102 |
| \(40\) | 221 |
| \(50\) | 350 |
| \(60\) | 751 |
| \(70\) | 951 |
| \(80\) | 997 |
Answer:
The mean age of \(1000\) persons is .
[Note: Enter the answer in to whole number.]