Marion and Bobby started running together along a cross country track. When Bobby completed the track in 38 minutes, Marion had run only
47 of the track. Marion’s average speed was 111 m/min slower than Bobby’s.
- How long was the cross country track in m?
- Find Marion’s average speed in m/min.
(a)
When Bobby completed the track:
Bobby's distance = 7 u
Marion's distance = 4 u
Extra distance covered by Bobby
= 7 u - 4 u
= 3 u
3 u = 111 x 38
3 u = 4218
1 u = 4218 ÷ 3 = 1406
Distance of the cross country track
= 7 u
= 7 x 1406
= 9842 m
(b)
Bobby's speed
= 9842 ÷ 38
= 259 m/min
Marion's speed
= 259 - 111
= 148 m/min
Answer(s): (a) 9842 m; (b) 148 m/min