Question:
Find the missing frequencies and the median for the following distribution if the mean is 1.46.
Solution:
(1) Let the missing frequencies be x and y.
Given:
$N=200$
$86+x+y=200$
$x=114-y \quad \ldots . .(1)$
We know that mean, $\bar{X}=\frac{\sum f_{i} x_{i}}{\sum f_{i}}$
$1.46=\frac{140+x+2 y}{200}$
$x+2 y+140=292$
$x+2 y=152$......(2)
Solving (1) and (2), we get
$114-y+2 y=152$
$y=38$
Therefore,
$x=114-38$
$=76$
Hence, the missing frequencies are 38 and 76.
(2) Calculation of median.
Now, we have $N=200$.
So, $\frac{N}{2}=100$
Thus, the cumulative frequency just greater than 100 is 122 and the value corresponding to 122 is 1.
Hence, the median is 1.