The table shows the age distribution in years of a group of people
Age(in years) | 1 – 5 | 6 – 10 | 11 – 15 | 16 – 20 | 21 – 25 | 26 – 30 |
Number of people | 18 | 12 | 25 | 15 | 20 | 10 |
Using an assume mean of 13 years, find the mean age of the people.
Explanation
Age | Class Mark(x) | Freq(f) | d = x – A | Fd |
1 – 5 | 3 | 18 | -10 | -180 |
6 – 10 | 8 | 12 | -5 | -60 |
11 – 15 | 13 | 25 | 0 | 0 |
16 – 20 | 18 | 15 | 5 | 75 |
21 – 25 | 23 | 20 | 10 | 200 |
26 – 30 | 28 | 10 | 15 | 150 |
Total | 100 | 185 |
Where A is the assumed mean = 13
substituting, mean = 13 + (frac{18}{100}) = 13 + 1.85
= 14.85 years