Joelle and Archie started off from the same place and drove at uniform speeds in the same direction round a 60 km circular racing track. Joelle completed each round in 60 minutes. Archie took 80 minutes to complete each round.
- How far would Archie be behind Joelle after 1 hour?
- How long after they started would it take Joelle to meet Archie for the first time? Express your answer as a whole or mixed number in h.
(a)
60 min = 1 h
1 min =
160 h
60 min =
6060 h = 1 h
80 min =
8060 h = 1
13 h
Joelle's speed
= 60 ÷ 1
= 60 x
11= 60 km/h
Archie's speed
= 60 ÷ 1
13= 60 x
34= 45 km/h
Distance between Joelle and Archie after 1 hour
= 60 - 45
= 15 km
(b)
LCM of 60 and 80 = 240
240 min =
24060 h = 4 h
Time needed for Joelle to meet Archie for the first time = 4 h
Answer(s): (a) 15 km; (b) 4 h