Question

A bullet train can travel 150 km in 30 mins. If the speed increases to 10 km/min , then find the time required to cover the same distance.

• A. 40 min
• B. 80 min
• C. 20 min
• D. 15 min

Answer 1

The correct option is D 15 min

Given, a bullet train can travel 150 km in 30 mins.

$\text{Hence, speed}=\frac{150}{30}=5km/min$

We know that, if the speed increases, the time required to cover the same distance will be less.

$\text{So, Speed}\left(x\right)\propto \frac{1}{\text{Time}\left(y\right)}$

$\therefore \frac{x_1}{x_2}=\frac{y_2}{y_1}$

Given,
$x_1=5km/min$
$y_1=30min$
$x_2=10km/min$
$\text{and}{y}_2=\text{time required}$

$\Rightarrow \frac{5}{10}=\frac{y_2}{30}$
$\Rightarrow y_2=\frac{30\times 5}{10}=15min$