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Question
In the class, weight of students is measured for the class records. Calculate mean weight of the class students using direct method
| Weight in kg | 15 − 25 | 25 − 35 | 35 − 45 | 45 − 55 | 55 − 65 | 65 − 75 |
| No. of students | 4 | 11 | 19 | 14 | 0 | 2 |
Sum
Solution
| Weight in (kg) |
Mid value (x) |
No. of students (f) |
fx |
| 15 − 25 | 20 | 4 | 80 |
| 25 − 35 | 30 | 11 | 330 |
| 35 − 45 | 40 | 19 | 760 |
| 45 − 55 | 50 | 14 | 700 |
| 55 − 65 | 60 | 0 | 0 |
| 65 − 75 | 70 | 2 | 140 |
| `sumf` = 50 | `sumfx` = 2010 |
Arithmetic mean `bar(x) = (sumfx)/(sumf)`
= `2010/50`
= 40.2
Arithmetic mean = 40.2
shaalaa.com
Method of Finding Mean for Grouped Data: Direct Method
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