Kimberly and Ethan started off from the same place and drove at uniform speeds in the same direction round a 60 km circular racing track. Kimberly completed each round in 40 minutes. Ethan took 80 minutes to complete each round.
- How far would Ethan be behind Kimberly after 1 hour?
- How long after they started would it take Kimberly to meet Ethan for the first time? Express your answer as a whole or mixed number in h.
(a)
60 min = 1 h
1 min =
160 h
40 min =
4060 h =
23 h
80 min =
8060 h = 1
13 h
Kimberly's speed
= 60 ÷
23= 60 x
32= 90 km/h
Ethan's speed
= 60 ÷ 1
13= 60 x
34= 45 km/h
Distance between Kimberly and Ethan after 1 hour
= 90 - 45
= 45 km
(b)
LCM of 40 and 80 = 80
80 min =
8060 h = 1
13 h
Time needed for Kimberly to meet Ethan for the first time = 1
13 h
Answer(s): (a) 45 km; (b) 1
13 h