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 NO SPAMMING PLZ

Given:

Let T be the time taken for the entire journey.

Total DISTANCE = 100m

Average speed for entire journey =30km/ 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 70km/ h

Time taken to cover part of journey: t1

t1= 30km÷ 30km/ h

t1=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.

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