At 200 km track a train travels first 50 km at a uniform speed of 40 km/h how far the train was travelling the next 150 km so as to maintain the average speed of 60 km/h for the whole journey
Answers
Answer:
The train’s speed by maintaining the average speed 60 km/hr for the next 150 km is 72 km/hr.
Given:
Initial distance = 50 km
Total distance = 200 km
Speed = 40 km/h
To find:
The fast of the train to cover next 150 km so as to maintain the average speed of 60 km/h
Solution:
For first 50 km, the speed is 40 km/hr =\frac{50}{40}=\frac{5}{4} \ \mathrm{km} / \mathrm{hr}=
40
50
=
4
5
km/hr
Let x be the km for the next 150 km.
\text { Time taken for the } 150 \ \mathrm{km}=\frac{150}{x} \ \mathrm{hr} Time taken for the 150 km=
x
150
hr
\text{Total time taken} =\frac{5}{4}+\frac{150}{x}=\frac{5 x+600}{4 x} h rTotal time taken=
4
5
+
x
150
=
4x
5x+600
hr
\text { Average speed }=\frac{\text { Total distance }}{\text { Total time taken }} Average speed =
Total time taken
Total distance
\Rightarrow 500 x=36000⇒500x=36000
\Rightarrow x=\frac{36000}{500}⇒x=
500
36000
\therefore x=72 \ \mathrm{km} / \mathrm{hr}∴x=72 km/hr
Explanation:
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