Question

A goods train in five successive minutes from its starts run 68 metres, 127 metres, 208 metres, 312 metres, and 535 , metres, and for the next 5 minutes, maintains an average speed of 33 km/hr in covering this total distance,

• A. 20 km / hr
• B. 30 km / hr
• C. 28 km / hr
• D. 24 km / hr

Answer 1

The correct option is D 24 km / hr

In first 5min.=$\frac{5}{60}hr=\frac{1}{12}hr,$ the train covers $(68+127+208+312+535)m=1250m=1.25km$.

In the last $5min=\frac{1}{12}hr,$ the train runs at a speed of 33$\frac{km}{hr}$.

$\therefore$ Distance covered $=$ speed $\times$ time $=33\times \frac{1}{12}km=2.75km$

$\therefore$ total time taken=$\frac{1}{12}hr$ +$\frac{1}{12}hr$ =$\frac{1}{6}hr$ &

the total distance covered $=1.25km+2.75km=4km$.

$\therefore$ The average speed=$\frac{Totaldistancecovered}{Totaltimetaken}=\frac{4}{\frac{1}{6}}\frac{km}{hr}=24\frac{km}{hr}.$

Ans- Option D.