Cindy and David started off from the same place and drove at uniform speeds in the same direction round a 35 km circular racing track. Cindy completed each round in 50 minutes. David took 100 minutes to complete each round.
- How far would David be behind Cindy after 1 hour?
- How long after they started would it take Cindy to meet David 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
Cindy's speed
= 35 ÷
56= 35 x
65= 42 km/h
David's speed
= 35 ÷ 1
23= 35 x
35= 21 km/h
Distance between Cindy and David after 1 hour
= 42 - 21
= 21 km
(b)
LCM of 50 and 100 = 100
100 min =
10060 h = 1
23 h
Time needed for Cindy to meet David for the first time = 1
23 h
Answer(s): (a) 21 km; (b) 1
23 h