Question

The distance between two station is 200km.the train covers first 100 km with speed of 500km/hr.at what speed should the train travel the next 100 km, so that the average speed becomes 70km/hr

Answer 1

Hii...
Here is your answer..

Solution:-
Let time be x
Average speed =Total Distance/Total time
$= > 70 = \frac{200}{x} \\ = > x = \frac{200}{70} = \frac{20}{7}$
Distance travelled 1st time =100m
Speed =500km/h
So,
Time =D/S
$= > \frac{100}{500} = \frac{1}{5}h$
Distance travelled 2nd time =100m
Speed = let it be x
Time =D/S
$= > \frac{100}{x}$
A/q
$= > \frac{20}{7} = \frac{1}{5} + \frac{100}{x} \\ = > \frac{20}{7} - \frac{1}{5} = \frac{100}{x} \\ = > \frac{100 - 7}{35} = \frac{100}{x}$
$= > \frac{93}{35} = \frac{100}{x} \\ = > x = \frac{35 \times 100}{93} \\ = > x = 37.63$
Hence,
He should travel next 100km with speed of 37km/h(approx)

Hope it helps uh...✌️✌️✌️