Irene and Mark started off from the same place and drove at uniform speeds in the same direction round a 40 km circular racing track. Irene completed each round in 50 minutes. Mark took 100 minutes to complete each round.
- How far would Mark be behind Irene after 1 hour?
- How long after they started would it take Irene to meet Mark 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
100 min =
10060 h = 1
23 h
Irene's speed
= 40 ÷
56= 40 x
65= 48 km/h
Mark's speed
= 40 ÷ 1
23= 40 x
35= 24 km/h
Distance between Irene and Mark after 1 hour
= 48 - 24
= 24 km
(b)
LCM of 50 and 100 = 100
100 min =
10060 h = 1
23 h
Time needed for Irene to meet Mark for the first time = 1
23 h
Answer(s): (a) 24 km; (b) 1
23 h