PSLE At a swimathon, each participant completed either a 3-km route, a 5-km route or a 7-km route.
13 of the participants completed the 3-km route,
37 of the participants completed the 5-km route and the rest completed the 7-km route. For every 1 km a participant swam, $6 was donated to charity. A total of $10908 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 5-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 -
13 -
37 = 1 -
721 -
921= 1 -
1621 =
521 Ratio of participants who completed the different routes
3 km : 5 km : 7 km
7 : 9 : 5
(b)
For every 1 km a participant swam, $6 was donated to charity.
Total distance covered by the participants
= 10908 ÷ 6
= 1818 km
|
3-km |
5-km |
7-km |
Total |
Number |
7 u |
9 u |
5 u |
21 u |
Value |
3 |
5 |
7 |
|
Total value |
21 u |
45 u |
35 u |
|
Total distance that the participants covered
= 3 x 7 u + 5 x 9 u + 7 x 5 u
= 21 u + 45 u + 35 u
= 101 u
101 u = 1818
1 u = 1818 ÷ 101 = 18
Total number of participants
= 7 u + 9 u + 5 u
= 21 u
= 21 x 18
= 378
Answer(s): (a) 7 : 9 : 5; (b) 378