PSLE At first, a box contained 71 white marbles and some black beads. After some white marbles were removed,
47 of the marbles were black. After 24 pink marbles were added to the box and now,
49 of the beads were black. What was the number of white marbles removed?
|
Black marbles |
White marbles |
Pink marbles |
Total |
Before |
4 u |
71 |
0 |
|
Change 1 |
|
- ? |
|
+ ? |
After 1 |
4 u |
3 u |
0 |
7 u |
Change 2 |
|
|
+ 24 |
+ 2 u |
After 2 |
4 u |
3 u |
2 u |
9 u |
Some white marbles were removed at first. However, when 24 pink marbles were added, the number of white marbles remains unchanged.
Number of pink marbles added
= 9 u - 7 u
= 2 u
2 u = 24
1 u = 24 ÷ 2 = 12
Number of white marbles removed
= 71 - 3 u
= 71 - 3 x 12
= 71 - 36
= 35
Answer(s): 35