Question:
Find the missing frequency (p) for the following distribution whose mean is 7.68.
Solution:
It is given that,
Mean = 7.68
$\Rightarrow \sum f_{x} / N=7.68$
⇒ 9p + 303p + 41 = 7.68
⇒ 9p + 303 = 7.68p + 314.88
⇒ 9p − 7.68p = 314.88 − 303
⇒ 1.32p = 11.88
⇒ p = 11.881.32 = 9
⇒ p = 9
∴ p = 9.