Anna and John started running together along a cross country track. When John completed the track in 21 minutes, Anna had run only
37 of the track. Anna’s average speed was 100 m/min slower than John’s.
- How long was the cross country track in m?
- Find Anna’s average speed in m/min.
(a)
When John completed the track:
John's distance = 7 u
Anna's distance = 3 u
Extra distance covered by John
= 7 u - 3 u
= 4 u
4 u = 100 x 21
4 u = 2100
1 u = 2100 ÷ 4 = 525
Distance of the cross country track
= 7 u
= 7 x 525
= 3675 m
(b)
John's speed
= 3675 ÷ 21
= 175 m/min
Anna's speed
= 175 - 100
= 75 m/min
Answer(s): (a) 3675 m; (b) 75 m/min