Question

Sujal covers a distance in $40$ min, if she drives at a speed of $60$ km/h on an average . Find the speed at which she must drive at to reduce the time of the journey by $25\%$.

• A. $60$ km/h
• B. $7$0 km/h
• C. $75$ km/h
• D. $80$ km/h

Answer 1

Answer: (D)

$80$ km/h

Given speed $=60$ kmph
It means Sujal covered $60$ km in $60$ min ($1$ hour). So, in $40$ min she will cover $40$ km.
$25\%$ time reduced $=40-25\%$ of $40=30$ min
Thus, Sujal need to cover $40$ km in $30$ min ($0.5$ hour)
Speed $\times$ Time $=$ Distance
Speed $\times 0.5=40$
Speed $=80$ kmph.