Lucy and Justin started running together along a cross country track. When Justin completed the track in 39 minutes, Lucy had run only
13 of the track. Lucy’s average speed was 98 m/min slower than Justin’s.
- How long was the cross country track in m?
- Find Lucy’s average speed in m/min.
(a)
When Justin completed the track:
Justin's distance = 3 u
Lucy's distance = 1 u
Extra distance covered by Justin
= 3 u - 1 u
= 2 u
2 u = 98 x 39
2 u = 3822
1 u = 3822 ÷ 2 = 1911
Distance of the cross country track
= 3 u
= 3 x 1911
= 5733 m
(b)
Justin's speed
= 5733 ÷ 39
= 147 m/min
Lucy's speed
= 147 - 98
= 49 m/min
Answer(s): (a) 5733 m; (b) 49 m/min