Risa has a bag containing some pink and purple beads. If she adds in 7 pink beads, 10% of the beads in the bag are purple. If she adds in another 72 purple beads, 50% of the beads in the bag are purple. How many pink beads are in the bag?
| |
Pink beads |
Purple beads |
| Before |
9 u - 7 |
1 u |
| Change 1 |
+ 7 |
|
| After 1 |
9x1 =
9 u |
1x1 =
1 u |
| Change 2 |
|
+ 72 |
| After 2 |
1x9 =
9 u |
1x9 =
9 u |
10% =
10100 =
11050% =
50100 =
12The number of pink beads remains unchanged at the second change when she adds in another 72 purple beads. Make the number of pink beads the same at the second change. LCM of 9 and 1 is 9.
Number of purple beads added
= 9 u - 1 u
= 8 u
8 u = 72
1 u = 72 ÷ 8 = 9
Number of pink beads at first
= 9 u - 7
= 9 x 9 - 7
= 81 - 7
= 74
Answer(s): 74
