PSLE A box contained red and gold beads. At first, the number of red beads was
16 the number of gold beads. After
12 of the red beads and
78 of the gold beads were used, 50 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?
|
Red |
Gold |
Comparing red beads and gold beads at first |
1x4 = 4 u |
6x4 = 24 u
|
Before
|
2x2 = 4 u |
8x3 = 24 u |
Change
|
- 1x2 = - 2 u |
- 7x3 = - 21 u |
After
|
1x2 = 2 u |
1x3 = 3 u |
(a)
The number of gold beads at first is repeated. Make the number of gold beads at first the same. LCM of 6 and 8 is 24.
The number of red beads at first is repeated.
Since the number of red beads at first is 4 u, we make the total number of red beads at first the same by multiplying 2 by 2 to become 4 u too.
Fraction of the beads used
=
2 + 214 + 24 =
2328 (b)
Number of beads left
= 2 u + 3 u
= 5 u
5 u = 50
1 u = 50 ÷ 5 = 10
Number of beads at first
= 28 u
= 28 x 10
= 280
Answer(s): (a)
2328; (b) 280