Tiffany and Joelle started off at the same spot and ran at average speeds round a 3-km circular path. Tiffany took 15 minutes to complete each round. Joelle completed each round in 28 minutes.
- How far ahead of Joelle would Tiffany be after 7 minute? Express your answer in metres.
- How long would it take Tiffany to meet Joelle for the first time?
- How many rounds would Tiffany have completed by then?
(a)
Tiffany's speed =
315 =
15 km/min
Joelle's speed =
328 km/min
Difference in speeds
=
15 -
328=
28140 -
15140=
13140 km/min
Distance between Tiffany and Joelle after 7 min
= 7 x
13140=
91140 km
1 km = 1000 m
91140 km =
91140 x 1000 = 650
(b)
LCM of 15 and 28 = 420
60 min = 1 h
420 min = 420 ÷ 60 = 7
Tiffany and Joelle will meet for the first time after 7 h.
(c)
Rounds Tiffany completed
= 420 ÷ 15
= 28
Answer(s): (a) 650 m; (b) 7 h; (c) 28