13 days ago, Jen had a total of 220 red and purple marbles. 25% of her marbles were purple marbles. Today, her grandfather gave her some more marbles. As a result, her red marbles increased by 20%. Now, 50% of her marbles are purple marbles. How many purple marbles did her grandfather give her?
| |
Purple marbles |
Red marbles |
Total
marbles |
| Before |
1 u |
3 u |
220 |
| Change |
+ 2.6 u |
+ 0.6 u |
|
| After |
3.6 u |
3.6 u |
|
Comparing the
red marbles and
purple marbles in the end |
1 |
1 |
|
25% =
25100 =
14 Purple marbles : Red marbles = 1 : 3
Increase in the number of red marbles
= 20% x 3 u
=
20100 x 3 u
= 0.6 u
50% =
50100 =
12 In the end
Purple marbles : Red marbles = 1 : 1
Number of marbles at first
= 3 u + 1 u
= 4 u
4 u = 220
1 u = 220 ÷ 4 = 55
Number of purple marbles that Jen received from her grandfather
= 3.6 u - 1 u
= 2.6 u
= 2.6 x 55
= 143
Answer(s): 143
