Zoe bought a total of 75 big and small chocolate bars. Then she decided to exchange 50% of her big chocolate bars for the small ones in the ratio of 1 : 5. After the exchange, she had 87 chocolate bars. What percentage of the chocolate bars she bought were small ones?
|
Big chocolate bars |
Small chocolate bars |
Total |
Before |
2 u |
? |
75 |
Change |
- 1 u |
|
|
Comparing big and small chocolate bars at exchange |
- 1 u |
+ 5 u |
+ 12 |
After |
1 u |
? |
87 |
50% =
50100 =
12The number of big chocolate bars that were exchanged for small chocolate bars was repeated.
Number of extra chocolate bars that Zoe received due to the exchange
= 5 u - 1 u
= 4 u
4 u = 87 - 75
4 u = 12
1 u = 12 ÷ 4 = 3
Number of small chocolate bars at first
= 75 - 2 u
= 75 - 2 x 3
= 75 - 6
= 69
Percentage of the chocolate bars Zoe bought that were small ones
=
6975 x 100%
= 92%
Answer(s): 92%