Mathematics
The following table gives the ages of 50 students of a class. Find the arithmetic mean of their ages.
| Age (years) | No. of students |
|---|---|
| 16 - 18 | 2 |
| 18 - 20 | 7 |
| 20 - 22 | 21 |
| 22 - 24 | 17 |
| 24 - 26 | 3 |
Measures of Central Tendency
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Answer
| Age (years) | Mid value (x) | No. of students (f) | fx |
|---|---|---|---|
| 16 - 18 | 17 | 2 | 34 |
| 18 - 20 | 19 | 7 | 133 |
| 20 - 22 | 21 | 21 | 441 |
| 22 - 24 | 23 | 17 | 391 |
| 24 - 26 | 25 | 3 | 75 |
| Total | Σf = 50 | Σfx = 1074 |
By formula,
Mean = = 21.48
Hence, mean = 21.48
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Related Questions
If the mean of the data given in adjoining table is 20, the relation between x1 and x2 is :
x f fx 10 x1 20 20 30 x2 x1 + x2 = 30
x1 - x2 = 15
x1 - x2 = 0
x1 + x2 = 20
The mean of data, represented by given diagram is :
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The following are the marks obtained by 70 boys in a class test.
Marks No. of boys 30 - 40 10 40 - 50 12 50 - 60 14 60 - 70 12 70 - 80 9 80 - 90 7 90 - 100 6 Calculate the mean by :
(i) Short-cut method
(ii) Step-deviation method
Find mean by 'step-deviation method' :
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