Opal and Riordan started running together along a cross country track. When Riordan completed the track in 21 minutes, Opal had run only
13 of the track. Opal’s average speed was 104 m/min slower than Riordan’s.
- How long was the cross country track in m?
- Find Opal’s average speed in m/min.
(a)
When Riordan completed the track:
Riordan's distance = 3 u
Opal's distance = 1 u
Extra distance covered by Riordan
= 3 u - 1 u
= 2 u
2 u = 104 x 21
2 u = 2184
1 u = 2184 ÷ 2 = 1092
Distance of the cross country track
= 3 u
= 3 x 1092
= 3276 m
(b)
Riordan's speed
= 3276 ÷ 21
= 156 m/min
Opal's speed
= 156 - 104
= 52 m/min
Answer(s): (a) 3276 m; (b) 52 m/min