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Question
If the mean of the following data is 18.75. Find the value of p.
| x | 10 | 15 | P | 25 | 30 |
| f | 5 | 10 | 7 | 8 | 2 |
Solution
| x | f | fx |
| 10 | 5 | 50 |
| 15 | 10 | 150 |
| P | 7 | 7P |
| 25 | 8 | 200 |
| 30 | 2 | 60 |
| N = 32 | `sum`fx = 7P + 460 |
Given
Mean = 18.75
`rArr(sumfx)/N=18.75`
`rArr(7P + 460)/32=18.75`
⇒ 7P + 460 = 18.75(32)
⇒ 7P + 460 = 600
⇒ 7P = 600 - 460
⇒ 7P = 140
`rArrP=140/7`
⇒ P = 20
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