Foundation
Mathematics Foundation
Time Speed Distance
Question

A thief escaped from police custody. Since he was sprinter he could clock 40 km/hr. The police realized if after 3 hr. and started chasing him in the same direction at 50 km /hr. The police had a dog which could run at 60 km/hr. The dog could run to the thief and then return to the police and then would turn back to wards the thief. It kept on doing so till the police caught the thief. Find the total distance travelled by the dog in the  direction of the thief.

720 km

660 km

360 km

600 km

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Solution
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Total time taken by the police in catching the thief = 40×35040=12hr 

Total distance travelled by the dog = 12 × 60 = 720 km

Total distance travelled by the dog in the direction of the thief = 720×60×50(60+50)+(6050)=720×1112 = 660 km