PSLE A box contained red and green beads. At first, the number of red beads was
13 the number of green beads. After
15 of the red beads and
710 of the green beads were used, 119 beads were left.
- What fraction of the beads were left? Leave your answer in the simplest form.
- How many beads were used?
|
Red |
Green |
Comparing red beads and green beads at first |
1x10 = 10 u |
3x10 = 30 u
|
Before
|
5x2 = 10 u |
10x3 = 30 u |
Change
|
- 1x2 = - 2 u |
- 7x3 = - 21 u |
After
|
4x2 = 8 u |
3x3 = 9 u |
(a)
The number of green beads at first is repeated. Make the number of green 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 left
=
8 + 910 + 30 =
1740 (b)
Number of beads left
= 8 u + 9 u
= 17 u
17 u = 119
1 u = 119 ÷ 17 = 7
Number of beads used
= 2 u + 21 u
= 23 u
= 23 x 7
= 161
Answer(s): (a)
1740; (b) 161