Ian had three bags of soya beans, P, Q and R and the mass of each bag of soya beans was in the ratio 3 : 3 : 2. Ian decided to transfer 10% of soya beans from Bag P into Bag Q and 80% of soya beans from Bag R into Bag Q. Given that the mass of Bag Q was 39.2 kg in the end, how many kilograms of soya beans were transferred into Bag Q?

	P	Q	R
Before	3 u	3 u	2 u
Change 1	- 0.3 u	+ 0.3 u
Change 2		+ 1.6 u	- 1.6 u
After	2.7 u	4.9 u	0.4 u

Mass of soya beans transferred from Bag P into Bag Q
= 10% x 3 u
= ¹⁰₁₀₀ x 3 u
= 2.7 u

Mass of soya beans transferred from Bag R into Bag Q
= 80% x 2 u
= ⁸⁰₁₀₀ x 2 u
= 1.6 u

Mass of soya beans in Bag Q in the end
= 3 u + 0.3 u + 1.6 u
= 4.9 u

4.9 u = 39.2 

1 u = 39.2 ÷ 4.9 = 8

Mass of soya beans transferred into Bag Q
= 0.3 u + 1.6 u
= 1.9 u
= 1.9 x 8
= 15.2 kg

Answer(s): 15.2 kg