5 days ago, Gillian had a total of 200 grey and red beads. 20% of her beads were red beads. Today, her older brother gave her some more beads. As a result, her grey beads increased by 10%. Now, 50% of her beads are red beads. How many red beads did her older brother give her?
| |
Red beads |
Grey beads |
Total
beads |
| Before |
1 u |
4 u |
200 |
| Change |
+ 3.4 u |
+ 0.4 u |
|
| After |
4.4 u |
4.4 u |
|
Comparing the
grey beads and
red beads in the end |
1 |
1 |
|
20% =
20100 =
15 Red beads : Grey beads = 1 : 4
Increase in the number of grey beads
= 10% x 4 u
=
10100 x 4 u
= 0.4 u
50% =
50100 =
12 In the end
Red beads : Grey beads = 1 : 1
Number of beads at first
= 4 u + 1 u
= 5 u
5 u = 200
1 u = 200 ÷ 5 = 40
Number of red beads that Gillian received from her older brother
= 4.4 u - 1 u
= 3.4 u
= 3.4 x 40
= 136
Answer(s): 136
