Question

If the mean of the given data is 250, then find the value of p.

$\begin{array}{cc}\text{Class interval}& \text{Frequency}\\ 0-100& 7\\ 100-200& 11\\ 200-300& 15\\ 300-400& p\\ 400-500& 8\end{array}$ [2 MARKS]

Answer 1

Concept: 1 Mark
Application: 1 Mark

$\begin{array}{ccc}\text{Class Marks}& \text{Frequency}& f_i{x}_i\\ 50& 7& 350\\ 150& 11& 1650\\ 250& 15& 3750\\ 350& p& 350p\\ 450& 8& 3600\end{array}$

$\sum f_i=41+p$ and $\sum f_i{x}_i=9350+350p$

$\frac{9350+350p}{41+p}=250$

$9350+350p=10250+250p$

$100p=900$

$p=9$