Risa and Ian started running together along a cross country track. When Ian completed the track in 21 minutes, Risa had run only
13 of the track. Risa’s average speed was 96 m/min slower than Ian’s.
- How long was the cross country track in m?
- Find Risa’s average speed in m/min.
(a)
When Ian completed the track:
Ian's distance = 3 u
Risa's distance = 1 u
Extra distance covered by Ian
= 3 u - 1 u
= 2 u
2 u = 96 x 21
2 u = 2016
1 u = 2016 ÷ 2 = 1008
Distance of the cross country track
= 3 u
= 3 x 1008
= 3024 m
(b)
Ian's speed
= 3024 ÷ 21
= 144 m/min
Risa's speed
= 144 - 96
= 48 m/min
Answer(s): (a) 3024 m; (b) 48 m/min