PSLE
At first, a box contained 5 purple marbles and some pink beads. After some purple marbles were added, 37 of the marbles were pink. After 52 grey marbles were added to the box and now, 311 of the beads were pink. What was the number of purple marbles added?
|
Pink marbles |
Purple marbles |
Grey marbles |
Total |
Before |
3 u |
5 |
0 |
|
Change 1 |
|
+ ? |
|
+ ? |
After 1 |
3 u |
4 u |
0 |
7 u |
Change 2 |
|
|
+ 52 |
+ 4 u |
After 2 |
3 u |
4 u |
4 u |
11 u |
Some purple marbles were added at first. However, when 52 grey marbles were added, the number of purple marbles remains unchanged.
Number of grey marbles added
= 11 u - 7 u
= 4 u
4 u = 52
1 u = 52 ÷ 4 = 13
Number of purple marbles added
= 4 u - 5
= 4 x 13 - 5
= 52 - 5
= 47
Answer(s): 47