Gabby and Dana started off at the same spot and ran at average speeds round a 3-km circular path. Gabby took 15 minutes to complete each round. Dana completed each round in 20 minutes.
- How far ahead of Dana would Gabby be after 7 minute? Express your answer in metres.
- How long would it take Gabby to meet Dana for the first time?
- How many rounds would Gabby have completed by then?
(a)
Gabby's speed =
315 =
15 km/min
Dana's speed =
320 km/min
Difference in speeds
=
15 -
320=
420 -
320=
120 km/min
Distance between Gabby and Dana after 7 min
= 7 x
120=
720 km
1 km = 1000 m
720 km =
720 x 1000 = 350
(b)
LCM of 15 and 20 = 60
60 min = 1 h
60 min = 60 ÷ 60 = 1
Gabby and Dana will meet for the first time after 1 h.
(c)
Rounds Gabby completed
= 60 ÷ 15
= 4
Answer(s): (a) 350 m; (b) 1 h; (c) 4