PSLE At a swimathon, each participant completed either a 1-km route, a 4-km route or a 7-km route.
15 of the participants completed the 1-km route,
13 of the participants completed the 4-km route and the rest completed the 7-km route. For every 1 km a participant swam, $10 was donated to charity. A total of $10080 was donated to charity.
- What is the ratio of the number of participants who completed the 1-km route to the number who completed the 4-km route to the number who completed the 7-km route?
- What is the total number of participants at the swimathon?
(a)
Fraction of the participants who completed 7-km route
= 1 -
15 -
13 = 1 -
315 -
515= 1 -
815 =
715 Ratio of participants who completed the different routes
1 km : 4 km : 7 km
3 : 5 : 7
(b)
For every 1 km a participant swam, $10 was donated to charity.
Total distance covered by the participants
= 10080 ÷ 10
= 1008 km
|
1-km |
4-km |
7-km |
Total |
Number |
3 u |
5 u |
7 u |
15 u |
Value |
1 |
4 |
7 |
|
Total value |
3 u |
20 u |
49 u |
|
Total distance that the participants covered
= 1 x 3 u + 4 x 5 u + 7 x 7 u
= 3 u + 20 u + 49 u
= 72 u
72 u = 1008
1 u = 1008 ÷ 72 = 14
Total number of participants
= 3 u + 5 u + 7 u
= 15 u
= 15 x 14
= 210
Answer(s): (a) 3 : 5 : 7; (b) 210