Fabian, George and Dylan started walking at the same time from the same starting point round a circular track. Dylan walked in the clockwise direction. Fabian and George walked in an anti-clockwise direction. Dylan took 6 min to complete each round. He met Fabian after every 3 minutes. He met George after every 5 minutes. The three friends kept to their respective speeds throughout their walk.
- How many rounds did Dylan complete in 1 h?
- When Dylan and Fabian met again at the starting point after 1 h, George had completed 1.8 km. Find the circumference of the circular track in metres.
(a)
1 h = 60 min
Number of rounds that Dylan completed in 1 h
= 60 ÷ 6
= 10
(b)
Dylan took 6 min to complete 1 round
1 min =
16 of circular track = 1 u
6 min =
66 of circular track = 6 u
Dylan's distance is the repeated identity.
Make Dylan's distance the same.
Dylan's distance : Fabian's distance
3 : 6 - 3
3 : 3
Dylan's distance : George's distance
5 : 6 - 5
5 : 1
Dylan |
Fabian |
George |
3x5 |
3x5 |
|
5x3 |
|
1x3 |
15 |
15 |
3 |
The distance of Dylan is the repeated identity.
LCM of 3 and 5 = 15
In 1 h
Dylan's rounds : Fabian's rounds : George's rounds
15 : 15 : 3
Distance that George completed in 1 h = 1.8 km
3 rounds = 1.8 km = 1800 m
1 round = 1800 ÷ 3 = 600 m
Circumference of the circular track = 600 m
Answer(s): (a) 10; (b) 600 m