a race car driver must average 203 km/h over the course of a time trial lasting ten laps. If the first nine laps were done at 199.0 km/h what average speed must be maintained for the last lap?

speed for last lap is 247.89 km/h

Explanation:

given data

velocity v1 = 203 km/h

velocity v2 = 199 km/h

no of lap n = 10

to find out

average speed for last lap

solution

we consider here distance d for 1 lap

so in first 9 lap time taken is

t1 = distance / velocity v2

t1 = 9d / 199 ... 1

and

for 10 lap time is

t2 = 10d / 203 ... 2

so from 1 and 2 equation time for last lap

last lap time t3 = t2 - t1

t3 = 10d / 203 - 9d / 199

t3 = 0.004034 d

so speed for last lap is

speed = distance / time

speed = d / 0.004034 d

speed = 247.89 km/h

so speed for last lap is 247.89 km/h