On a 100km track , a train travels the first 30km with a speed of 30km/h . How fast the train travel the next 70 km if the average speed for the entire journey is 40km/h?
Answers
Answer:
no
Explanation:
because first 30 km the train travels 30km/h,
for next 70km the train train travels 35km/h or 70km per/h
Answer:
Given:
Let T be the time taken for the entire journey.
Total DISTANCE = 100m
Average speed for entire journey =40km/ h
As we know:
Average speed= TOTAL DISTANCE/
TOTAL time
Total time =100/40=10/4 hours
Time taken to cover first part of journey be t1.
Distance covered is 30km .
Average speed to cover 30km is 30km/ h
Time taken to cover part of journey: t1
t1= 30km/ 30km/ h
=1 hr
Time taken to cover second part of journey be t2
Distance covered is 70km
Let x be the average speed for covering 70km
Time t2=70/X
Total time= T=t1 + t2
=1+70/x
Total time is 10/ 4 hrs
So,
10/4 =70/x + 1
10/4=(70+ x)/x
5/2=(70+x)/x
5x =2 (70+x)
5x=140+2x
5x-2x=140
3x=140
X=140/3
=46.66km/ h
Therefore Train must travel at a average speed of 46.66 km/ h to cover 70km.