There are two parallel streets each directed north to south. A person in the first street travelling from south to north wishes to take the second street which is on his right side. At some place, he makes a 150 deg turn to the right and he travels for 15 minutes at the speed of 20 km/hr. After that he takes a left turn of 60 deg and travels for 20 minutes at the speed of 30 km/hr in order to meet the second street. What is the distance between the two streets?

Correct Answer: 12.5 km

Explanation:

Initially the person is travelling from south to north i.e. D to A

He takes 150 deg right turn and moves AB distance and then he takes 60 deg left turn travels BC

AB = 20km/hr * 15/60 hr = 5km

BC = 30 * 20/60 = 10 km

We know that distance between both the streets is DC = DB + BC

DB = AB cos 60o= 5. ½ =2.5 km

So the distance between streets = 12.5 km

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