Craig ran the first part of a race with an average speed of 8 miles per hour and biked the second part of a race with an average speed of 20 miles per hour. The entire two-part, 15-mile race took him 1.125 hours to complete. Which table correctly represents his rates, times, and distances for each part of the race?

Question

Mathematics

Mo

21 November, 01:41

Craig ran the first part of a race with an average speed of 8 miles per hour and biked the second part of a race with an average speed of 20 miles per hour. The entire two-part, 15-mile race took him 1.125 hours to complete. Which table correctly represents his rates, times, and distances for each part of the race?

+1

Answers (1)

Know the Answer?

Rudy Jacobs · Answer 1

Let the distance of the first part of the race be x, and that of the second part, 15 - x, then

x/8 + (15 - x) / 20 = 1.125

5x + 2 (15 - x) = 40 x 1.125

5x + 30 - 2x = 45

3x = 45 - 30 = 15

x = 15/3 = 5

Therefore, the distance of the first part of the race is 5 miles and the time is 5/8 = 0.625 hours or 37.5 minutes

The distance of the second part of the race is 15 - 5 = 10 miles and the time is 1.125 - 0.625 = 0.5 hours or 30 minutes.