Question 81

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

Solution

Distance = Speed $$\times$$ Time

Initial speed = 70 kmph

In first 2 hours, motor covers a distance = $$70 \times 2 = 140~km$$

Speed after 2 hours = 70 + 10 = 80 kmph

In the next 2 hours, it covers a distance = $$80 \times 2 = 160~km$$

Distance covered = 300 km

Now, the speed is 90 kmph

Remaining 45 km is covered in $$\frac{45}{90}$$ = 0.5 hr

Total time taken to cover 345 km = 2 + 2 + 0.5 = 4.5 hr

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