Question

A car travels a distance of $170$ km in $2$ hours, partly at a speed of $100$ km/hr and partly at $50$ km/hr. The distance travelled at the speed of $50$ km/hr is

• A. $50$ km
• B. $40$ km
• C. $30$ km
• D. $60$ km

Answer 1

The correct option is C $30$ km

Let the distance travelled at 100 km/hr be x km.

Then, distance travelled at 50 km/hr is (170 - x) km.

Given, $\frac{x}{100}+\frac{(170-x)}{50}=2$

$\Rightarrow \frac{x+2(170-x)}{100}=2\Rightarrow x+240-2x=200$

$\Rightarrow x=140km.$

$\therefore$ Distance travelled at 50 km/hr $=(170-140)km=30km$