Gabriel, Perry and Liam started walking at the same time from the same starting point round a circular track. Liam walked in the clockwise direction. Gabriel and Perry walked in an anti-clockwise direction. Liam took 12 min to complete each round. He met Gabriel after every 2 minutes. He met Perry after every 6 minutes. The three friends kept to their respective speeds throughout their walk.
- How many rounds did Liam complete in 1 h?
- When Liam and Gabriel met again at the starting point after 1 h, Perry had completed 2.1 km. Find the circumference of the circular track in metres.
(a)
1 h = 60 min
Number of rounds that Liam completed in 1 h
= 60 ÷ 12
= 5
(b)
Liam took 12 min to complete 1 round
1 min =
112 of circular track = 1 u
12 min =
1212 of circular track = 12 u
Liam's distance is the repeated identity.
Make Liam's distance the same.
Liam's distance : Gabriel's distance
2 : 12 - 2
2 : 10
Liam's distance : Perry's distance
6 : 12 - 6
6 : 6
Liam |
Gabriel |
Perry |
2x3 |
10x3 |
|
6x1 |
|
6x1 |
6 |
30 |
6 |
The distance of Liam is the repeated identity.
LCM of 2 and 6 = 6
In 1 h
Liam's rounds : Gabriel's rounds : Perry's rounds
6 : 30 : 6
Distance that Perry completed in 1 h = 2.1 km
6 rounds = 2.1 km = 2100 m
1 round = 2100 ÷ 6 = 350 m
Circumference of the circular track = 350 m
Answer(s): (a) 5; (b) 350 m