Sainik School Entrance Exam 2019 Solved Paper

(c) Suppose that the upper and lower limits of the class are $\mathit{p}$ and $\mathit{q}$ then,
$\frac{\mathit{p}+\mathit{q}}{2}=42$
$\mathit{p}+\mathit{q}=84$ ............................(1)
$\mathit{p}-\mathit{q}=10$ ..............................(2)
On adding equation (1) + equation (2), we get,
$2\mathit{p}=94$
$\mathit{p}=47$
From equation (1),
$47+\mathit{q}=84$
$\mathit{q}=37$
∴ Class interval are 37 and 47 .