Luis, John and Daniel started walking at the same time from the same starting point round a circular track. Daniel walked in the clockwise direction. Luis and John walked in an anti-clockwise direction. Daniel took 6 min to complete each round. He met Luis after every 2 minutes. He met John after every 5 minutes. The three friends kept to their respective speeds throughout their walk.
- How many rounds did Daniel complete in 1 h?
- When Daniel and Luis met again at the starting point after 1 h, John had completed 2.9 km. Find the circumference of the circular track in metres.
(a)
1 h = 60 min
Number of rounds that Daniel completed in 1 h
= 60 ÷ 6
= 10
(b)
Daniel took 6 min to complete 1 round
1 min =
16 of circular track = 1 u
6 min =
66 of circular track = 6 u
Daniel's distance is the repeated identity.
Make Daniel's distance the same.
Daniel's distance : Luis's distance
2 : 6 - 2
2 : 4
Daniel's distance : John's distance
5 : 6 - 5
5 : 1
Daniel |
Luis |
John |
2x5 |
4x5 |
|
5x2 |
|
1x2 |
10 |
20 |
2 |
The distance of Daniel is the repeated identity.
LCM of 2 and 5 = 10
In 1 h
Daniel's rounds : Luis's rounds : John's rounds
10 : 20 : 2
Distance that John completed in 1 h = 2.9 km
2 rounds = 2.9 km = 2900 m
1 round = 2900 ÷ 2 = 1450 m
Circumference of the circular track = 1450 m
Answer(s): (a) 10; (b) 1450 m