Asher, Peter and Jenson started walking at the same time from the same starting point round a circular track. Jenson walked in the clockwise direction. Asher and Peter walked in an anti-clockwise direction. Jenson took 6 min to complete each round. He met Asher after every 2 minutes. He met Peter after every 5 minutes. The three friends kept to their respective speeds throughout their walk.

1. How many rounds did Jenson complete in 1 h?
2. When Jenson and Asher met again at the starting point after 1 h, Peter had completed 2.5 km. Find the circumference of the circular track in metres.

(a)
1 h = 60 min

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

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

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

Jenson's distance : Asher's distance
2 : 6 - 2
2 : 4

Jenson's distance : Peter's distance
5 : 6 - 5
5 : 1

Jenson	Asher	Peter
2x5	4x5
5x2		1x2
10	20	2

The distance of Jenson is the repeated identity. 
LCM of 2 and 5 = 10

In 1 h
Jenson's rounds : Asher's rounds : Peter's rounds
10 : 20 : 2

Distance that Peter completed in 1 h = 2.5 km

2 rounds = 2.5 km = 2500 m

1 round = 2500 ÷ 2 = 1250 m

Circumference of the circular track = 1250 m

Answer(s): (a) 10; (b) 1250 m