PSLE At first, a container contained 77 yellow balls and some purple beads. After some yellow balls were removed,
310 of the balls were purple. After 12 gold balls were added to the container and now,
314 of the beads were purple. What was the number of yellow balls removed?
|
Purple balls |
Yellow balls |
Gold balls |
Total |
Before |
3 u |
77 |
0 |
|
Change 1 |
|
- ? |
|
+ ? |
After 1 |
3 u |
7 u |
0 |
10 u |
Change 2 |
|
|
+ 12 |
+ 4 u |
After 2 |
3 u |
7 u |
4 u |
14 u |
Some yellow balls were removed at first. However, when 12 gold balls were added, the number of yellow balls remains unchanged.
Number of gold balls added
= 14 u - 10 u
= 4 u
4 u = 12
1 u = 12 ÷ 4 = 3
Number of yellow balls removed
= 77 - 7 u
= 77 - 7 x 3
= 77 - 21
= 56
Answer(s): 56