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
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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
