PSLE
At first, a box contained 5 purple marbles and some red beads. After some purple marbles were added, 38 of the marbles were red. After 42 pink marbles were added to the box and now, 311 of the beads were red. What was the number of purple marbles added?
|
Red marbles |
Purple marbles |
Pink marbles |
Total |
Before |
3 u |
5 |
0 |
|
Change 1 |
|
+ ? |
|
+ ? |
After 1 |
3 u |
5 u |
0 |
8 u |
Change 2 |
|
|
+ 42 |
+ 3 u |
After 2 |
3 u |
5 u |
3 u |
11 u |
Some purple marbles were added at first. However, when 42 pink marbles were added, the number of purple marbles remains unchanged.
Number of pink marbles added
= 11 u - 8 u
= 3 u
3 u = 42
1 u = 42 ÷ 3 = 14
Number of purple marbles added
= 5 u - 5
= 5 x 14 - 5
= 70 - 5
= 65
Answer(s): 65