PSLE A box contained red and silver beads. At first, the number of red beads was
13 the number of silver beads. After
35 of the red beads and
110 of the silver beads were used, 248 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 |
Silver |
Comparing red beads and silver beads at first |
1x10 = 10 u |
3x10 = 30 u
|
Before
|
5x2 = 10 u |
10x3 = 30 u |
Change
|
- 3x2 = - 6 u |
- 1x3 = - 3 u |
After
|
2x2 = 4 u |
9x3 = 27 u |
(a)
The number of silver beads at first is repeated. Make the number of silver beads at first the same. LCM of 3 and 10 is 30.
The number of red beads at first is repeated.
Since the number of red beads at first is 10 u, we make the total number of red beads at first the same by multiplying 5 by 2 to become 10 u too.
Fraction of the beads used
=
6 + 310 + 30 =
940 (b)
Number of beads left
= 4 u + 27 u
= 31 u
31 u = 248
1 u = 248 ÷ 31 = 8
Number of beads at first
= 40 u
= 40 x 8
= 320
Answer(s): (a)
940; (b) 320