Dana and Joelle started off at the same spot and ran at average speeds round a 3-km circular path. Dana took 15 minutes to complete each round. Joelle completed each round in 20 minutes.
- How far ahead of Joelle would Dana be after 3 minute? Express your answer in metres.
- How long would it take Dana to meet Joelle for the first time?
- How many rounds would Dana have completed by then?
(a)
Dana's speed =
315 =
15 km/min
Joelle's speed =
320 km/min
Difference in speeds
=
15 -
320=
420 -
320=
120 km/min
Distance between Dana and Joelle after 3 min
= 3 x
120=
320 km
1 km = 1000 m
320 km =
320 x 1000 = 150
(b)
LCM of 15 and 20 = 60
60 min = 1 h
60 min = 60 ÷ 60 = 1
Dana and Joelle will meet for the first time after 1 h.
(c)
Rounds Dana completed
= 60 ÷ 15
= 4
Answer(s): (a) 150 m; (b) 1 h; (c) 4