Kathy and Justin started off from the same place and drove at uniform speeds in the same direction round a 60 km circular racing track. Kathy completed each round in 50 minutes. Justin took 90 minutes to complete each round.
- How far would Justin be behind Kathy after 1 hour?
- How long after they started would it take Kathy to meet Justin for the first time? Express your answer as a whole or mixed number in h.
(a)
60 min = 1 h
1 min =
160 h
50 min =
5060 h =
56 h
90 min =
9060 h = 1
12 h
Kathy's speed
= 60 ÷
56= 60 x
65= 72 km/h
Justin's speed
= 60 ÷ 1
12= 60 x
23= 40 km/h
Distance between Kathy and Justin after 1 hour
= 72 - 40
= 32 km
(b)
LCM of 50 and 90 = 450
450 min =
45060 h = 7
12 h
Time needed for Kathy to meet Justin for the first time = 7
12 h
Answer(s): (a) 32 km; (b) 7
12 h