The distance between delhi and agra is 200km. a train travels the first 100 km at a speed of 50 km/h . how fast must the train travel the next 100 km, so as to average 70 km/h for the whole journey?
Answers
Answered by
3
d1+d2/1+100/x
70=100+100/1+100/x
70(x+100/x)=200
70(x+100)=200x
x+100=200x/770
x+100=20x
x=20x-100/7
x=80x/7
70=100+100/1+100/x
70(x+100/x)=200
70(x+100)=200x
x+100=200x/770
x+100=20x
x=20x-100/7
x=80x/7
Answered by
3
Here,
Total distance
= 200 km
Average speed
= 70 km/h
Total taken time :-
= Total distance/Average speed
= 200/70
= 20/7 hour
1st part of Journey :-
Distance = 100 km
Speed = 50 km/h
Now,
Time taken,
t1 = 100/50
t1 = 2 hour
Now
2nd part Journey,
Distance = 100 km
Here,
Speed = p km/h
Time taken,
t2 = (100/p) hour
So,
t1 + t2 = 20/7
2 + (100/p) = 20/7
p = 116.6 km/h
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