PSLE Nora had a total of 41 silver and purple beads. She used 11 silver beads and 60% of the purple beads. After that, the ratio of the number of silver beads to purple beads Nora had was 1 : 2.
- What fraction of her purple beads did Nora use? Give your answer in the simplest form.
- How many beads did Nora have in the end?
|
Silver beads |
Purple beads |
Total |
Before |
1 u + 11 |
5 u |
6 u + 11 |
Change |
- 11 |
- 3 u |
|
After |
1 u |
2 u |
3 u |
Comparing silver beads and purple beads in the end |
1 |
2 |
3 |
(a)
60% =
60100 =
35 Fraction of her purple beads that Nora used =
35 (b)
The number of purple beads in the end is repeated.
Since the numbers are already the same, we do not need to use LCM to make them the same.
Number of purple beads at first = 5 u
Number of silver beads at first = 1 u + 11
Total number of beads at first
= 5 u + 1 u + 11
= 6 u + 11
6 u + 11 = 41
6 u = 41 - 11
6 u = 30
1 u = 30 ÷ 6 = 5
Number of purple beads in the end = 2 u
Number of silver beads in the end = 1 u
Total number of beads in the end
= 1 u + 2 u
= 3 u
= 3 x 5
= 15
Answer(s): (a)
35; (b) 15