Mary bought a total of 350 big and small sweets. Then she decided to exchange 40% of her big sweets for the small ones in the ratio of 2 : 7. After the exchange, she had 385 sweets. What percentage of the sweets she bought were small ones?
| |
Big sweets |
Small sweets |
Total |
| Before |
5 u |
? |
350 |
| Change |
- 2 u |
|
|
Comparing big and
small sweets at exchange |
- 2 u |
+ 7 u |
+ 35 |
| After |
3 u |
? |
385 |
40% =
40100 =
25The number of big sweets that were exchanged for small sweets was repeated.
Number of extra sweets that Mary received due to the exchange
= 7 u - 2 u
= 5 u
5 u = 385 - 350
5 u = 35
1 u = 35 ÷ 5 = 7
Number of small sweets at first
= 350 - 5 u
= 350 - 5 x 7
= 350 - 35
= 315
Percentage of the sweets Mary bought that were small ones
=
315350 x 100%
= 90%
Answer(s): 90%
