Kimberly and David started off from the same place and drove at uniform speeds in the same direction round a 40 km circular racing track. Kimberly completed each round in 40 minutes. David took 50 minutes to complete each round.
- How far would David be behind Kimberly after 1 hour?
- How long after they started would it take Kimberly 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
40 min =
4060 h =
23 h
50 min =
5060 h =
56 h
Kimberly's speed
= 40 ÷
23= 40 x
32= 60 km/h
David's speed
= 40 ÷
56= 40 x
65= 48 km/h
Distance between Kimberly and David after 1 hour
= 60 - 48
= 12 km
(b)
LCM of 40 and 50 = 200
200 min =
20060 h = 3
13 h
Time needed for Kimberly to meet David for the first time = 3
13 h
Answer(s): (a) 12 km; (b) 3
13 h