Sarah and Julian started off from the same place and drove at uniform speeds in the same direction round a 30 km circular racing track. Sarah completed each round in 40 minutes. Julian took 60 minutes to complete each round.
- How far would Julian be behind Sarah after 1 hour?
- How long after they started would it take Sarah to meet Julian 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
60 min =
6060 h = 1 h
Sarah's speed
= 30 ÷
23= 30 x
32= 45 km/h
Julian's speed
= 30 ÷ 1
= 30 x
11= 30 km/h
Distance between Sarah and Julian after 1 hour
= 45 - 30
= 15 km
(b)
LCM of 40 and 60 = 120
120 min =
12060 h = 2 h
Time needed for Sarah to meet Julian for the first time = 2 h
Answer(s): (a) 15 km; (b) 2 h