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  • A police man was travelling @ 90kmph. He crosses a thief travelling @ 60kmph in opposite direction.

A police man was travelling at 90kmph. He crosses a thief travelling at 60kmph in opposite direction. He had to travel for another 6 minutes before he would U turn and chase the thief? After they crossed each other how long in minutes police will catch the thief?

 

  • Option 1)

     

    30

     

  • Option 2)

     

    36

     

  • Option 3)

     

    35

     

  • Option 4)

     

    45

     

  • Option 5)

     

    42

Answers (1)

best_answer

Speed of policeman = 90 km/h
Speed of thief $=\mathbf{6 0 ~ k m} / \mathbf{h}$
They are travelling in opposite directions when they first cross each other.
Policeman continues forward for 6 minutes before making a U-turn to chase.

6 minutes $=\frac{6}{60}=0.1$ hours

Relative speed while going in opposite directions $=90+60=150 \mathrm{~km} / \mathrm{h}$.
In 0.1 hours, distance between them increases by:

$
150 \times 0.1=15 \mathrm{~km}
$
So when the policeman turns, the thief is $\mathbf{1 5} \mathbf{~ k m}$ away ahead of him.

Now both move in the same direction:

$
\text { Relative speed }=90-60=30 \mathrm{~km} / \mathrm{h}
$

$\begin{gathered}\text { Time }=\frac{\text { Distance }}{\text { Relative speed }}=\frac{15}{30}=0.5 \text { hours } \\ 0.5 \text { hours }=30 \text { minutes }\end{gathered}$

 

Posted by

rishi.raj

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