PSLE A box contained green and black beads. At first, the number of green beads was
13 the number of black beads. After
35 of the green beads and
910 of the black beads were used, 28 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 |
Black |
Comparing green beads and black beads at first |
1x10 = 10 u |
3x10 = 30 u
|
Before
|
5x2 = 10 u |
10x3 = 30 u |
Change
|
- 3x2 = - 6 u |
- 9x3 = - 27 u |
After
|
2x2 = 4 u |
1x3 = 3 u |
(a)
The number of black beads at first is repeated. Make the number of black beads at first the same. LCM of 3 and 10 is 30.
The number of green beads at first is repeated.
Since the number of green beads at first is 10 u, we make the total number of green beads at first the same by multiplying 5 by 2 to become 10 u too.
Fraction of the beads used
=
6 + 2710 + 30 =
3340 (b)
Number of beads left
= 4 u + 3 u
= 7 u
7 u = 28
1 u = 28 ÷ 7 = 4
Number of beads at first
= 40 u
= 40 x 4
= 160
Answer(s): (a)
3340; (b) 160