Yen and Jane started off at the same spot and ran at average speeds round a 3-km circular path. Yen took 15 minutes to complete each round. Jane completed each round in 20 minutes.
- How far ahead of Jane would Yen be after 4 minute? Express your answer in metres.
- How long would it take Yen to meet Jane for the first time?
- How many rounds would Yen have completed by then?
(a)
Yen's speed =
315 =
15 km/min
Jane's speed =
320 km/min
Difference in speeds
=
15 -
320=
420 -
320=
120 km/min
Distance between Yen and Jane after 4 min
= 4 x
120=
420 km
1 km = 1000 m
420 km =
420 x 1000 = 200
(b)
LCM of 15 and 20 = 60
60 min = 1 h
60 min = 60 ÷ 60 = 1
Yen and Jane will meet for the first time after 1 h.
(c)
Rounds Yen completed
= 60 ÷ 15
= 4
Answer(s): (a) 200 m; (b) 1 h; (c) 4