Risa and Michael started running together along a cross country track. When Michael completed the track in 50 minutes, Risa had run only
49 of the track. Risa’s average speed was 115 m/min slower than Michael’s.
- How long was the cross country track in m?
- Find Risa’s average speed in m/min.
(a)
When Michael completed the track:
Michael's distance = 9 u
Risa's distance = 4 u
Extra distance covered by Michael
= 9 u - 4 u
= 5 u
5 u = 115 x 50
5 u = 5750
1 u = 5750 ÷ 5 = 1150
Distance of the cross country track
= 9 u
= 9 x 1150
= 10350 m
(b)
Michael's speed
= 10350 ÷ 50
= 207 m/min
Risa's speed
= 207 - 115
= 92 m/min
Answer(s): (a) 10350 m; (b) 92 m/min