Yvette ran at an average speed of 6.20 ft/s during the first two a race and an average speed of 7.75 ft/s during the second two laps of a race. What was Yvette's average speed for the entire race? Round to the nearest tenth.

6.7 ft/s

Step-by-step explanation:

distance = speed * time

time = distance/speed

Assume the race distance was 200 ft (it doesn't matter what distance we choose).

For the first 100 ft: time = 100 ft * 1 s/6.20 ft = 16.13 s

For the second 100 ft: time = 100 ft * 1 s/7.75 ft = 12.90 s

For the whole 200 ft: total time = 29.03 s

Average speed = total distance/total time = 200 ft/29.03 s = 6.7 ft/s