Find the mean age of 100 residents of a town from the following data :
Age equal and above (in years) | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 |
Number of Persons | 100 | 90 | 75 | 50 | 25 | 15 | 5 | 0 |
Answer. [31]
Solution. Here we calculate mean by following the given steps:
Marks | xi | fi | |
0-10 | 5 | 100-90 =10 | 50 |
10-20 | 15 | 90-75 = 15 | 225 |
20-30 | 25 | 75-50 = 25 | 625 |
30-40 | 35 | 50-25 =25 | 875 |
40-50 | 45 | 25-15 =10 | 450 |
50-60 | 55 | 15-5 = 10 | 550 |
60-70 | 65 | 5-0 = 5 | 325 |