During a telematch, each group of students was supposed to collect as many coloured balls as possible. Each colour represented a certain point as tabulated:
| Colours |
Points |
| Black |
3 |
| Red |
4 |
| White |
5 |
In each container, the number of black balls was 40% more than the number of white balls and 50% less than the number of red balls. Given that the total possible points if the group managed to collect all the balls were 306 points, how many balls were not black in colour?
| Black |
Red |
White |
| 7x1 |
|
5x1 |
| 1x7 |
2x7 |
|
| 7 u |
14 u |
5 u |
| |
Black |
Red |
White |
Total |
| Number |
7 u |
14 u |
5u |
|
| Value |
3 |
4 |
5 |
|
| Total value |
21 u |
56 u |
25 u |
102 u |
100% + 40% = 140%
140% =
140100 =
75 100% - 50% = 50%
50% =
50100 =
12 Total number of points collected
= 21 u + 56 u + 25 u
= 102 u
102 u = 306
1 u = 306 ÷ 102 = 3
Number of balls not red in colour
= 7 u + 5 u
= 12 u
= 12 x 3
= 36
Answer: 36
