Abi made muffins for sale. 55% of the muffins were beef muffins and the rest were chicken and chocolate muffins in the ratio 3 : 1. If a customer bought 75% of the beef muffins and all of the chocolate muffins, what percentage of the chicken muffins must Abi sell for her to maintain the original percentage of beef muffins at first? Leave your answer in decimals and correct to 1 decimal place.

Beef muffins	Chicken muffins	Chocolate muffins
11 u	9 u
	6.75 u	2.25 u

	Beef muffins	Chicken muffins	Chocolate muffins	Total muffins
Before	11 u	6.75 u	2.25 u	20 u
Change	- 8.25 u	- 4.5 u	- 2.25 u
After	2.75 u	2.25 u	0	5 u

55% = ⁵⁵₁₀₀ = ¹¹₂₀
75% = ⁷⁵₁₀₀ = ³₄

Total number of muffins = 20 u

Number of chicken and chocolate muffins
= 20 u - 11 u
= 9 u

Number of chicken muffins at first
= ³₄ x 9 u
= 6.75 u

Number of chocolate muffins at first
= 9 u - 6.75 u
= 2.25 u

Number of beef muffins sold
= 75% x 11 u
= ⁷⁵₁₀₀ x 11 u
= ³₄ x 11 u
= 8.25 u

Number of chocolate muffins sold
= ¹₄ x 9 u
= 2.25 u

Number of beef muffins left 
= 11 u - 8.25 u
= 2.75 u

To maintain the percentage of the beef muffins in the end, 
55% → 2.75 u
100% → ^2.75₅₅ x 100 = 5 u

Total number of muffins in the end to maintain the original percentage of beef muffins = 5 u

Number of chicken muffins left
= 5 u - 2.75 u
= 2.25 u

Number of chicken muffins that Abi must sell to maintain the original percentage of beef muffins
= 6.75 u - 2.25 u
= 4.5 u

Percentage of the chicken muffins that Abi must sell
= ^4.5_6.75 x 100%
= 66.7%

Answer(s): 66.7%