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Question
If the mean of the following data is 15, find p.
| x | 5 | 10 | 15 | 20 | 25 |
| f | 6 | P | 6 | 10 | 5 |
Solution
| x | f | fx |
| 5 | 6 | 30 |
| 10 | P | 10P |
| 15 | 6 | 90 |
| 20 | 10 | 200 |
| 25 | 5 | 125 |
| N = P + 27 | `sum` fx = 10P + 445 |
Given
⇒ Mean = 15
`rArr(sumfx)/N=15`
`rArr(10P+445)/(P+27)`
⇒ 10P + 445 = 15(P + 27)
⇒ 10P + 445 = 15P + 405
⇒ 15P - 10P = 445 - 405
⇒ 5P = 40
`rArrp=40/5`
⇒ P = 8
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