Ken, Ian and Flynn started walking at the same time from the same starting point round a circular track. Flynn walked in the clockwise direction. Ken and Ian walked in an anti-clockwise direction. Flynn took 6 min to complete each round. He met Ken after every 3 minutes. He met Ian after every 5 minutes. The three friends kept to their respective speeds throughout their walk.

1. How many rounds did Flynn complete in 1 h?
2. When Flynn and Ken met again at the starting point after 1 h, Ian had completed 1.2 km. Find the circumference of the circular track in metres.

(a)
1 h = 60 min

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

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

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

Flynn's distance : Ken's distance
3 : 6 - 3
3 : 3

Flynn's distance : Ian's distance
5 : 6 - 5
5 : 1

Flynn	Ken	Ian
3x5	3x5
5x3		1x3
15	15	3

The distance of Flynn is the repeated identity. 
LCM of 3 and 5 = 15

In 1 h
Flynn's rounds : Ken's rounds : Ian's rounds
15 : 15 : 3

Distance that Ian completed in 1 h = 1.2 km

3 rounds = 1.2 km = 1200 m

1 round = 1200 ÷ 3 = 400 m

Circumference of the circular track = 400 m

Answer(s): (a) 10; (b) 400 m