Mary and Carl started off from the same place and drove at uniform speeds in the same direction round a 40 km circular racing track. Mary completed each round in 40 minutes. Carl took 100 minutes to complete each round.
- How far would Carl be behind Mary after 1 hour?
- How long after they started would it take Mary to meet Carl 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
100 min =
10060 h = 1
23 h
Mary's speed
= 40 ÷
23= 40 x
32= 60 km/h
Carl's speed
= 40 ÷ 1
23= 40 x
35= 24 km/h
Distance between Mary and Carl after 1 hour
= 60 - 24
= 36 km
(b)
LCM of 40 and 100 = 200
200 min =
20060 h = 3
13 h
Time needed for Mary to meet Carl for the first time = 3
13 h
Answer(s): (a) 36 km; (b) 3
13 h