Question

A train covers 10 km in 2 hours, then it will cover km in 4 hours (the speed of the train is constant).

• A. 30
• B. 20
• C. 10
• D. 40

Answer 1

The correct option is B 20

Distance ∝ Time (Speed is constant).

We know that, if two quantities are directly proportional, then the ratio between the two quantities is constant.

$\frac{Distancetravelled}{Timetaken}=Constant$

$\begin{array}{ccc}\text{Distance(km)}& \text{10}& ?\\ Time\left(hr\right)& 2& 4\end{array}$

$\frac{10}{2}$ = $\frac{x}{4}$

$x=\frac{10\times 4}{2}$

$x=20km$

Therefore, distance covered by the train in 4 hours is 20 km.