2 days ago, Opal had a total of 275 purple and white stamps. 20% of her stamps were white stamps. Today, her older sister gave her some more stamps. As a result, her purple stamps increased by 10%. Now, 50% of her stamps are white stamps. How many white stamps did her older sister give her?
| |
White stamps |
Purple stamps |
Total
stamps |
| Before |
1 u |
4 u |
275 |
| Change |
+ 3.4 u |
+ 0.4 u |
|
| After |
4.4 u |
4.4 u |
|
Comparing the
purple stamps and
white stamps in the end |
1 |
1 |
|
20% =
20100 =
15 White stamps : Purple stamps = 1 : 4
Increase in the number of purple stamps
= 10% x 4 u
=
10100 x 4 u
= 0.4 u
50% =
50100 =
12 In the end
White stamps : Purple stamps = 1 : 1
Number of stamps at first
= 4 u + 1 u
= 5 u
5 u = 275
1 u = 275 ÷ 5 = 55
Number of white stamps that Opal received from her older sister
= 4.4 u - 1 u
= 3.4 u
= 3.4 x 55
= 187
Answer(s): 187
