Subject: General Aptitude · Chapter: Time and Distance · Exam: · Marks: · Difficulty:
A car travels from $P$ to $Q$ at a constant speed. If its speed were increased by 10 km/hr, it would have taken one hour lesser to cover the distance. It would have taken further 45 minutes lesser if the speed was further increased by 10 km/hr. What is the distance between the two cities?
(a)420 km
(b)540 km
(c)600 km
(d)650 km
Answer
Answer (as printed): A
Explanation
Let distance $=x \mathrm{km}$ and usual rate $=y \mathrm{kmph}$. Then, $$\frac{x}{y}-\frac{x}{y+10}=1 \text { or } y(y+10)=10 x$$ And $$\frac{x}{y}-\frac{x}{y+20}=\frac{7}{4} \text { or } y(y+20)=\frac{80 x}{7}$$ On dividing (i) by (ii), we get : $y=60$.