Barbara made muffins for sale. 55% of the muffins were lotus paste muffins and the rest were sardine and mushroom muffins in the ratio 3 : 1. If a customer bought 65% of the lotus paste muffins and all of the mushroom muffins, what percentage of the sardine muffins must Barbara sell for her to maintain the original percentage of lotus paste muffins at first? Leave your answer in decimals and correct to 1 decimal place.

Lotus paste muffins	Sardine muffins	Mushroom muffins
11 u	9 u
	6.75 u	2.25 u

	Lotus paste muffins	Sardine muffins	Mushroom muffins	Total muffins
Before	11 u	6.75 u	2.25 u	20 u
Change	- 7.15 u	- 3.6 u	- 2.25 u
After	3.85 u	3.15 u	0	7 u

55% = ⁵⁵₁₀₀ = ¹¹₂₀
65% = ⁶⁵₁₀₀ = ¹³₂₀

Total number of muffins = 20 u

Number of sardine and mushroom muffins
= 20 u - 11 u
= 9 u

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

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

Number of lotus paste muffins sold
= 65% x 11 u
= ⁶⁵₁₀₀ x 11 u
= ¹³₂₀ x 11 u
= 7.15 u

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

Number of lotus paste muffins left 
= 11 u - 7.15 u
= 3.85 u

To maintain the percentage of the lotus paste muffins in the end, 
55% → 3.85 u
100% → ^3.85₅₅ x 100 = 7 u

Total number of muffins in the end to maintain the original percentage of lotus paste muffins = 7 u

Number of sardine muffins left
= 7 u - 3.85 u
= 3.15 u

Number of sardine muffins that Barbara must sell to maintain the original percentage of lotus paste muffins
= 6.75 u - 3.15 u
= 3.6 u

Percentage of the sardine muffins that Barbara must sell
= ^3.6_6.75 x 100%
= 53.3%

Answer(s): 53.3%