Subject: General Aptitude · Chapter: Time and Distance · Exam: 2005 · Marks: · Difficulty:
A train travels at a speed of 30 km/hr for 12 minutes and at a speed of 45 km/hr for the next 8 minutes. The average speed of the train for this journey is
(a)30 km/hr
(b)36 km/hr
(c)37.5 km/hr
(d)48 km/hr
Answer
Answer (as printed): B
Explanation
Total distance travelled $=\left(30 \times \frac{12}{60}+45 \times \frac{8}{60}\right) \mathrm{km}=12 \mathrm{km}$. $$\begin{aligned} & \text { Total time taken }=(12+8) \mathrm{min}=20 \mathrm{min}=\frac{1}{3} \mathrm{hr} . \\ & \therefore \text { Average speed }=(12 \times 3) \mathrm{km} / \mathrm{hr}=36 \mathrm{km} / \mathrm{hr} . \end{aligned}$$