Subject: General Aptitude · Chapter: Time and Distance · Exam: · Marks: · Difficulty:
The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 kms in 4 hours, then the speed of the first train is
(a)70 km/hr
(b)75 km/hr
(c)84 km/hr
(d)87.5 km/hr
Answer
Answer (as printed): D
Explanation
Let the speeds of two trains be $7 x$ and $8 x \mathrm{km} / \mathrm{hr}$. $$\text { Then, } 8 x=\frac{400}{4}=100 \Rightarrow x=\left(\frac{100}{8}\right)=12.5 .$$ ∴ Speed of first train $=(7 \times 12.5) \mathrm{km} / \mathrm{hr}=87.5 \mathrm{km} / \mathrm{hr}$.