Winnie bought a total of 120 big and small sweets. Then she decided to exchange 30% of her big sweets for the small ones in the ratio of 3 : 7. After the exchange, she had 132 sweets. What percentage of the sweets she bought were small ones?
| |
Big sweets |
Small sweets |
Total |
| Before |
10 u |
? |
120 |
| Change |
- 3 u |
|
|
Comparing big and
small sweets at exchange |
- 3 u |
+ 7 u |
+ 12 |
| After |
7 u |
? |
132 |
30% =
30100 =
310The number of big sweets that were exchanged for small sweets was repeated.
Number of extra sweets that Winnie received due to the exchange
= 7 u - 3 u
= 4 u
4 u = 132 - 120
4 u = 12
1 u = 12 ÷ 4 = 3
Number of small sweets at first
= 120 - 10 u
= 120 - 10 x 3
= 120 - 30
= 90
Percentage of the sweets Winnie bought that were small ones
=
90120 x 100%
= 75%
Answer(s): 75%
