Question

$\begin{array}{cc}\text{Class interval}& \text{Class mark}\\ 0-10& A\\ 10-20& B\\ 20-30& 25\\ 30-40& 35\end{array}$

The value of A & B are:

• A. 2.5, 7.5
• B. 3, 7
• C. 2, 7
• D. 3,8

Answer 1

The correct option is A

2.5, 7.5

Class mark for a class interval = $\frac{\text{Upperclass limit + Lowerclass limit}}{2}$

For the 1^st class interval : upper class limit is 10 and the lower limit is 0.
Thus class mark = $\frac{10+0}{2}=5$

For the 2^nd class interval, the upper-class limit is 20 and the lower limit is 10.
Thus the class mark = $\frac{20+10}{2}=15$