Question

Angie runs 7 mph for the first half of a marathon, 13.1

miles, but twists her knee and must walk 2 mph for the
second half. What was her average speed? Round to 2
decimal places.

Answer 1

Explanation:

For the first half of the Marathon, we need to find the time.

t = d/r

r = 7 mph

d = 13.1

t = 13.1 / 7

t = 1.87 hours.

For the second half of the Marathon we need the time as well.

t = d/r

r = 2 mph

d = 13.1

t = 13.1 / 2

t = 6.55 hours.

Now to find the average speed, you will need the total time and the total distance

Total distance = 13.1 + 13.1 = 26.2 miles

Total time = t1 + t2

Total time = 1.87 hours + 6.55 hours.

Total time = 8.42

average speed = Total Distance / total time

average speed = 26.2 / 8.42 = 3.11 miles per hour