If the mean of the following data is 8, find the value of p.
x35791113f6815p84
We prepare the following frequency table:
(xi) | (fi) | xifi |
3 | 6 | 18 |
5 | 8 | 40 |
7 | 15 | 105 |
9 | p | 9p |
11 | 8 | 88 |
13 | 4 | 52 |
Σfi=41+p | Σfixi= 303+9p |
Mean =
Σfixi=303+9p
Σfi=41+p
But, mean = 8 (given)
Thus, we have:
8=303+9p41+p
⇒328+8p=303+9p
⇒p=25