Question

A train travels 12 km in the first quarter of an hour, 15 km in the second quarter and 30 km in the third quarter. Find the average speed of the train per hour over the entire journey

Answer 1

Answer:

76 km/hr

Explanation:

Avg speed=tot distance/tot time

Tot distance=(12+15+30)km => 57 km

Quareter of an hour = 25 minutes => 0.25 hr

Tot time=(0.25+0.25+0.25) => 0.75 hr

Avg speed=57/0.75 => 76 km/hr

Answer 2

Given:

Distance traveled in the first quarter $=12km$

Distance traveled in the second quarter $=15km$

Distance traveled in the third quarter $=30km$

To find:

Average speed of the train

Solution:

We know,

Average speed of any object is given by the total distance traveled by the object throughout the journey divided by the total time of the journey.

                              $S_{avg}= \frac{D}{T}$

We have been given the distance traveled by the train in 3 quarters of an hour .

Hence,

Total distance $=12+15+30$ $=57Km$

Total time $=3$ quarters $=3$ × $15=45min$ $=\frac{3}{4}hours$  

Hence,

$S_{avg} =\frac{57}{\frac{3}{4} }$

$S_{avg}=\frac{57*4}{3}$

$S_{avg}=76km/h$

Final answer:

Hence, the average speed of the train throughout the journey will be 76 km/h.