Yoko and Eva started off at the same spot and ran at average speeds round a 3-km circular path. Yoko took 15 minutes to complete each round. Eva completed each round in 20 minutes.
- How far ahead of Eva would Yoko be after 8 minute? Express your answer in metres.
- How long would it take Yoko to meet Eva for the first time?
- How many rounds would Yoko have completed by then?
(a)
Yoko's speed =
315 =
15 km/min
Eva's speed =
320 km/min
Difference in speeds
=
15 -
320=
420 -
320=
120 km/min
Distance between Yoko and Eva after 8 min
= 8 x
120=
820 km
1 km = 1000 m
820 km =
820 x 1000 = 400
(b)
LCM of 15 and 20 = 60
60 min = 1 h
60 min = 60 ÷ 60 = 1
Yoko and Eva will meet for the first time after 1 h.
(c)
Rounds Yoko completed
= 60 ÷ 15
= 4
Answer(s): (a) 400 m; (b) 1 h; (c) 4