Question

on a 200 km track A train travels the first 50 km at uniform speed of 40 km per hour how fast the train must travel the next 150 km so as to maintain the average speed of 60 km per hour for the whole journey

Answer 1

Hii..
Here is your answer..

Solution:-
Total length of train (Distance)=200km
Average speed=60km/h
Let time be x.
So,
$average \: speed = \frac{total \: distance}{total \:time }$
$60 = \frac{200}{x}$
$= \frac{200}{60} = \frac{10}{3}$
Now,
First Distance(D1)=50km
Speed first(S1)=40km/h
So,
Time =D/T
$= > \frac{50}{40} = \frac{5}{4}$
And,
Second Distance(D2)=150km
Let the second speed be x
So,
Time =D/S
$= > \frac{150}{x}$
A/q
$= > \frac{10}{3} = \frac{5}{4} + \frac{150}{x}$
$= > \frac{10}{3} - \frac{5}{4} = \frac{150}{x} \\ = > \frac{40 - 15}{12} = \frac{150}{x}$
$= > \frac{25}{12} = \frac{150}{x} \\ = > x = \frac{150 \times 12}{25}$
$= > x = \frac{1800}{25} \\ = > x = 72$
Hence,he should travel rest 150 at speed of 72km/h so that average speed is equal to 60km/h.

Hope it helps uh...✌️✌️✌️