A train moves with a speed of 30 kmph for 12 minutes and for next 8 minutes at a speed of 45 kmph. Find the average speed of the train?
A. 37.50 kmph
B. 36 kmph
C. 48 kmph
D. 30 kmph
Answer: Option B
Solution(By Examveda Team)
$$\eqalign{ & {\text{Distance = Speed }} \times {\text{Time}} \cr & {\text{Distance covered by train with the}} \cr & {\text{speed of 30 kmph in 12 minutes is }} \cr & {\text{ = 30}} \times \frac{{12}}{{60}} = 6{\text{km}} \cr & {\text{Distance covered by the same train}} \cr & {\text{with the speed of 45 kmph in 8 minutes is }} \cr & {\text{ = 45}} \times \frac{8}{{60}} = 6{\text{km}} \cr & {\text{Average speed}} \cr & {\text{ = }}\frac{{{\text{total distance}}}}{{{\text{total time}}}}. \cr & \Rightarrow \frac{{\left( {6 + 6} \right){\text{km}}}}{{\left( {12 + 8} \right)\min }} = \frac{{12}}{{20}} \times 60 \cr & {\text{ = 36 kmph}} \cr} $$Join The Discussion
Comments ( 1 )
Related Questions on Problems on Trains
A. 120 metres
B. 180 metres
C. 324 metres
D. 150 metres
A. 45 km/hr
B. 50 km/hr
C. 54 km/hr
D. 55 km/hr
A. 200 m
B. 225 m
C. 245 m
D. 250 m
Distance =Speed×Time
The distance covered by the train with the speed of 30 kmph in 12 minutes is
=30×1260=6km
Distance = Speed Time
The distance covered by the train with the speed of 45 kmph in 8 minutes is
=45×860=6km
Average speed=rac{Total Distance}{Total time}
=(6+6)km(12+8)min=1220×60
=36 kmph