Jen and Eric started running together along a cross country track. When Eric completed the track in 28 minutes, Jen had run only
13 of the track. Jen’s average speed was 100 m/min slower than Eric’s.
- How long was the cross country track in m?
- Find Jen’s average speed in m/min.
(a)
When Eric completed the track:
Eric's distance = 3 u
Jen's distance = 1 u
Extra distance covered by Eric
= 3 u - 1 u
= 2 u
2 u = 100 x 28
2 u = 2800
1 u = 2800 ÷ 2 = 1400
Distance of the cross country track
= 3 u
= 3 x 1400
= 4200 m
(b)
Eric's speed
= 4200 ÷ 28
= 150 m/min
Jen's speed
= 150 - 100
= 50 m/min
Answer(s): (a) 4200 m; (b) 50 m/min