Betty and Wendy started off at the same spot and ran at average speeds round a 4-km circular path. Betty took 16 minutes to complete each round. Wendy completed each round in 30 minutes.
- How far ahead of Wendy would Betty be after 9 minute? Express your answer in metres.
- How long would it take Betty to meet Wendy for the first time?
- How many rounds would Betty have completed by then?
(a)
Betty's speed =
416 =
14 km/min
Wendy's speed =
215 km/min
Difference in speeds
=
14 -
215=
1560 -
860=
760 km/min
Distance between Betty and Wendy after 9 min
= 9 x
760= 1
360 km
1 km = 1000 m
1
360 km = 1
360 x 1000 = 1050
(b)
LCM of 16 and 30 = 240
60 min = 1 h
240 min = 240 ÷ 60 = 4
Betty and Wendy will meet for the first time after 4 h.
(c)
Rounds Betty completed
= 240 ÷ 16
= 15
Answer(s): (a) 1050 m; (b) 4 h; (c) 15