A motor car starts with the speed of 70 km/hr with its speed increasing every two hours by 10 kmph. In how many hours will it cover 345 kms?

** Option:**

**A.**4 (1/2) hours

**B.**2 (1/4) hours

**C.**3 hours

**D.**cannot be determined

**Answer: A . 4 (1/2) hours**

** Justification:**

Distance covered in first 2 hours = (70 x 2) km = 140 km

Distance covered in next 2 hours = (80 x 2) km = 160 km

Remaining distance = 345 – (140 + 160) = 45 km.

Speed in the fifth hour = 90 km/hr

Time taken to cover 45 km = (45/90) hr = (1/2) hour

Therefore Total time taken = 2 + 2 + (1/2) = **4 (1/2)hrs**