Sarah and Seth started running together along a cross country track. When Seth completed the track in 43 minutes, Sarah had run only
47 of the track. Sarah’s average speed was 111 m/min slower than Seth’s.
- How long was the cross country track in m?
- Find Sarah’s average speed in m/min.
(a)
When Seth completed the track:
Seth's distance = 7 u
Sarah's distance = 4 u
Extra distance covered by Seth
= 7 u - 4 u
= 3 u
3 u = 111 x 43
3 u = 4773
1 u = 4773 ÷ 3 = 1591
Distance of the cross country track
= 7 u
= 7 x 1591
= 11137 m
(b)
Seth's speed
= 11137 ÷ 43
= 259 m/min
Sarah's speed
= 259 - 111
= 148 m/min
Answer(s): (a) 11137 m; (b) 148 m/min