PSLE At first, a box contained 64 white balls and some purple beads. After some white balls were removed,
35 of the balls were purple. After 36 red balls were added to the box and now,
37 of the beads were purple. What was the number of white balls removed?
|
Purple balls |
White balls |
Red balls |
Total |
Before |
3 u |
64 |
0 |
|
Change 1 |
|
- ? |
|
+ ? |
After 1 |
3 u |
2 u |
0 |
5 u |
Change 2 |
|
|
+ 36 |
+ 2 u |
After 2 |
3 u |
2 u |
2 u |
7 u |
Some white balls were removed at first. However, when 36 red balls were added, the number of white balls remains unchanged.
Number of red balls added
= 7 u - 5 u
= 2 u
2 u = 36
1 u = 36 ÷ 2 = 18
Number of white balls removed
= 64 - 2 u
= 64 - 2 x 18
= 64 - 36
= 28
Answer(s): 28