PSLE At a swimathon, each participant completed either a 3-km route, a 6-km route or a 9-km route.
12 of the participants completed the 3-km route,
25 of the participants completed the 6-km route and the rest completed the 9-km route. For every 1 km a participant swam, $9 was donated to charity. A total of $6480 was donated to charity.
- What is the ratio of the number of participants who completed the 3-km route to the number who completed the 6-km route to the number who completed the 9-km route?
- What is the total number of participants at the swimathon?
(a)
Fraction of the participants who completed 9-km route
= 1 -
12 -
25 = 1 -
510 -
410= 1 -
910 =
110 Ratio of participants who completed the different routes
3 km : 6 km : 9 km
5 : 4 : 1
(b)
For every 1 km a participant swam, $9 was donated to charity.
Total distance covered by the participants
= 6480 ÷ 9
= 720 km
|
3-km |
6-km |
9-km |
Total |
Number |
5 u |
4 u |
1 u |
10 u |
Value |
3 |
6 |
9 |
|
Total value |
15 u |
24 u |
9 u |
|
Total distance that the participants covered
= 3 x 5 u + 6 x 4 u + 9 x 1 u
= 15 u + 24 u + 9 u
= 48 u
48 u = 720
1 u = 720 ÷ 48 = 15
Total number of participants
= 5 u + 4 u + 1 u
= 10 u
= 10 x 15
= 150
Answer(s): (a) 5 : 4 : 1; (b) 150