PSLE A box contained blue and purple beads. At first, the number of blue beads was
13 the number of purple beads. After
12 of the blue beads and
14 of the purple beads were used, 55 beads were left.
- What fraction of the beads were left? Leave your answer in the simplest form.
- How many beads were used?
|
Blue |
Purple |
Comparing blue beads and purple beads at first |
1x4 = 4 u |
3x4 = 12 u
|
Before
|
2x2 = 4 u |
4x3 = 12 u |
Change
|
- 1x2 = - 2 u |
- 1x3 = - 3 u |
After
|
1x2 = 2 u |
3x3 = 9 u |
(a)
The number of purple beads at first is repeated. Make the number of purple beads at first the same.
LCM of 3 and 4 is 12.
The number of blue beads at first is repeated.
Since the number of blue beads at first is 4 u, we make the total number of blue beads at first the same by multiplying 2 by 2 to become 4 u too.
Fraction of the beads left
=
2 + 94 + 12 =
1116 (b)
Number of beads left
= 2 u + 9 u
= 11 u
11 u = 55
1 u = 55 ÷ 11 = 5
Number of beads used
= 2 u + 3 u
= 5 u
= 5 x 5
= 25
Answer(s): (a)
1116; (b) 25