Fabian, George and Justin started walking at the same time from the same starting point round a circular track. Justin walked in the clockwise direction. Fabian and George walked in an anti-clockwise direction. Justin took 6 min to complete each round. He met Fabian after every 2 minutes. He met George after every 4 minutes. The three friends kept to their respective speeds throughout their walk.

1. How many rounds did Justin complete in 1 h?
2. When Justin and Fabian met again at the starting point after 1 h, George had completed 2.8 km. Find the circumference of the circular track in metres.

(a)
1 h = 60 min

Number of rounds that Justin completed in 1 h
= 60 ÷ 6
= 10

(b)
Justin took 6 min to complete 1 round
1 min = ¹₆ of circular track = 1 u
6 min = ⁶₆ of circular track = 6 u

Justin's distance is the repeated identity.
Make Justin's distance the same.

Justin's distance : Fabian's distance
2 : 6 - 2
2 : 4

Justin's distance : George's distance
4 : 6 - 4
4 : 2

Justin	Fabian	George
2x2	4x2
4x1		2x1
4	8	2

The distance of Justin is the repeated identity. 
LCM of 2 and 4 = 4

In 1 h
Justin's rounds : Fabian's rounds : George's rounds
4 : 8 : 2

Distance that George completed in 1 h = 2.8 km

2 rounds = 2.8 km = 2800 m

1 round = 2800 ÷ 2 = 1400 m

Circumference of the circular track = 1400 m

Answer(s): (a) 10; (b) 1400 m