Question

The mid-value of a class interval is 42 and the class size is 10. The lower and upper limits are
(a) 37−47
(b) 37.5−47.5
(c) 36.5−47.5
(d) 36.5−46.5

Answer 1

(a) 37–47

Let the lower limit be x.
Here,
Class size = 10
∴ Upper limit = Class size + Lower limit
Upper limit = (x + 10)
Mid value of the class interval = 42

$$\begin{gathered} \therefore \frac{x+x+10}{2}=42 \\ \Rightarrow \frac{2x+10}{2}=42 \\ \Rightarrow 2x+10=84 \\ \Rightarrow 2x=74 \\ \Rightarrow x=37 \\ \mathrm{Thus},\mathrm{we}\mathrm{have}: \\ \mathrm{Lower}\mathrm{limit}=37 \\ \mathrm{Upper}\mathrm{limit}=37+10=47 \end{gathered}$$