PSLE A box contained yellow and orange beads. At first, the number of yellow beads was
13 the number of orange beads. After
14 of the yellow beads and
78 of the orange beads were used, 81 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?
|
Yellow |
Orange |
Comparing yellow beads and orange beads at first |
1x8 = 8 u |
3x8 = 24 u
|
Before
|
4x2 = 8 u |
8x3 = 24 u |
Change
|
- 1x2 = - 2 u |
- 7x3 = - 21 u |
After
|
3x2 = 6 u |
1x3 = 3 u |
(a)
The number of orange beads at first is repeated. Make the number of orange beads at first the same. LCM of 3 and 8 is 24.
The number of yellow beads at first is repeated.
Since the number of yellow beads at first is 8 u, we make the total number of yellow beads at first the same by multiplying 4 by 2 to become 8 u too.
Fraction of the beads used
=
2 + 218 + 24 =
2332 (b)
Number of beads left
= 6 u + 3 u
= 9 u
9 u = 81
1 u = 81 ÷ 9 = 9
Number of beads at first
= 32 u
= 32 x 9
= 288
Answer(s): (a)
2332; (b) 288