Risa and Howard started off from the same place and drove at uniform speeds in the same direction round a 55 km circular racing track. Risa completed each round in 50 minutes. Howard took 100 minutes to complete each round.
- How far would Howard be behind Risa after 1 hour?
- How long after they started would it take Risa to meet Howard 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
Risa's speed
= 55 ÷
56= 55 x
65= 66 km/h
Howard's speed
= 55 ÷ 1
23= 55 x
35= 33 km/h
Distance between Risa and Howard after 1 hour
= 66 - 33
= 33 km
(b)
LCM of 50 and 100 = 100
100 min =
10060 h = 1
23 h
Time needed for Risa to meet Howard for the first time = 1
23 h
Answer(s): (a) 33 km; (b) 1
23 h