The ratio between the rates of travelling of A and B is 2 : 3 and therefore A takes 20 min more than time taken by B to reach a destination. If A had walked at double the speed, how long would he have taken to cover the distance?
The ratio between the rates of travelling of A and B is 2 : 3 and therefore A takes 20 min more than time taken by B to reach a destination. If A had walked at double the speed, how long would he have taken to cover the distance?
A30 min
B35 min
C20 min
D45 min
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Correct answer is: 30 min
Explanation:
We know that speed is inversely proportional to time. Therefore,
Time taken by A : Time taken by B =
Let B takes x min. Then, A takes (x + 20) min.\(\therefore \left(x+20\right) : x = \frac{1}{2}:\frac{1}{3}=3:2\)
\(\implies \frac{x+20}{x}=\frac{3}{2} \implies 2x+40 = 3x\)
\(x=40 \)
\((x+20) \text{ or } \left(40+20\right) = 60 min\)
Therefore,
At double the speed, A would have covered it in 30 min.
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