The following table shows the weight (in kg) of 40 students of class X : Find the mean weight and median weight.

Solution
For Correct Table (2 Marks)
Mean $= A + \frac{\Sigma f_i u_i}{\Sigma f_i} \times h$
$= 57.5 + \frac{(-2)}{40} \times 5$ (1 Mark)
$= 57.25$ (1/2 Mark)
$\therefore$ The mean weight is $57.25$ kg
Median $= l + \frac{\frac{n}{2} - cf}{f} \times h$ (1 Mark)
$= 55 + \frac{20-17}{8} \times 5$ (1/2 Mark)
$= 56.87$
$\therefore$ The median weight is $56.87$ kg