PSLE A box contained green and purple beads. At first, the number of green beads was
13 the number of purple beads. After
34 of the green beads and
78 of the purple beads were used, 40 beads were left.
- What fraction of the beads were used? Leave your answer in the simplest form.
- How many beads were there in the box at first?
|
Green |
Purple |
Comparing green beads and purple beads at first |
1x8 = 8 u |
3x8 = 24 u
|
Before
|
4x2 = 8 u |
8x3 = 24 u |
Change
|
- 3x2 = - 6 u |
- 7x3 = - 21 u |
After
|
1x2 = 2 u |
1x3 = 3 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 8 is 24.
The number of green beads at first is repeated.
Since the number of green beads at first is 8 u, we make the total number of green beads at first the same by multiplying 4 by 2 to become 8 u too.
Fraction of the beads used
=
6 + 218 + 24 =
2732 (b)
Number of beads left
= 2 u + 3 u
= 5 u
5 u = 40
1 u = 40 ÷ 5 = 8
Number of beads at first
= 32 u
= 32 x 8
= 256
Answer(s): (a)
2732; (b) 256