Advertisements
Advertisements
प्रश्न
Using step-deviation method, find mean for the following frequency distribution:
| Class | 0 – 15 | 15 – 30 | 30 – 45 | 45 – 60 | 60 – 75 | 75 – 90 |
| Frequency | 3 | 4 | 7 | 6 | 8 | 2 |
योग
Advertisements
उत्तर
In the given table (i) is the class interval which is equal to 15.
| Class | Class mark (x) |
d = (x − A) | u = `bb(d/i)` | Frequency (f) |
fu |
| 0 – 15 | 7.5 | –45 | –3 | 3 | –9 |
| 15 – 30 | 22.5 | –30 | –2 | 4 | –8 |
| 30 – 45 | 37.5 | –15 | –1 | 7 | –7 |
| 45 – 60 | 52.5 → A | 0 | 0 | 6 | 0 |
| 60 – 75 | 67.5 | 15 | 1 | 8 | 8 |
| 75 – 90 | 82.5 | 30 | 2 | 2 | 4 |
| Total | `bb(sumf = 30)` | `bb(sumfu = –12)` |
Mean = `A + (sumfu)/(sumf) xx i`
= `52.5 + (-12)/30 xx 15`
= `52.5 - 180/30`
= 52.5 – 6
= 46.5
shaalaa.com
क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
