Irene and Cathy started off at the same spot and ran at average speeds round a 6-km circular path. Irene took 12 minutes to complete each round. Cathy completed each round in 25 minutes.
- How far ahead of Cathy would Irene be after 2 minute? Express your answer in metres.
- How long would it take Irene to meet Cathy for the first time?
- How many rounds would Irene have completed by then?
(a)
Irene's speed =
612 =
12 km/min
Cathy's speed =
625 km/min
Difference in speeds
=
12 -
625=
2550 -
1250=
1350 km/min
Distance between Irene and Cathy after 2 min
= 2 x
1350=
2650 km
1 km = 1000 m
2650 km =
2650 x 1000 = 520
(b)
LCM of 12 and 25 = 300
60 min = 1 h
300 min = 300 ÷ 60 = 5
Irene and Cathy will meet for the first time after 5 h.
(c)
Rounds Irene completed
= 300 ÷ 12
= 25
Answer(s): (a) 520 m; (b) 5 h; (c) 25