Betty and Emily started off at the same spot and ran at average speeds round a 6-km circular path. Betty took 12 minutes to complete each round. Emily completed each round in 25 minutes.
- How far ahead of Emily would Betty be after 8 minute? Express your answer in metres.
- How long would it take Betty to meet Emily for the first time?
- How many rounds would Betty have completed by then?
(a)
Betty's speed =
612 =
12 km/min
Emily's speed =
625 km/min
Difference in speeds
=
12 -
625=
2550 -
1250=
1350 km/min
Distance between Betty and Emily after 8 min
= 8 x
1350= 2
450 km
1 km = 1000 m
2
450 km = 2
450 x 1000 = 2080
(b)
LCM of 12 and 25 = 300
60 min = 1 h
300 min = 300 ÷ 60 = 5
Betty and Emily will meet for the first time after 5 h.
(c)
Rounds Betty completed
= 300 ÷ 12
= 25
Answer(s): (a) 2080 m; (b) 5 h; (c) 25