Sam had three bags of corn starch, X, Y and Z and the mass of each bag of corn starch was in the ratio 3 : 4 : 1. Sam decided to transfer 40% of corn starch from Bag X into Bag Y and 90% of corn starch from Bag Z into Bag Y. Given that the mass of Bag Y was 30.5 kg in the end, how many kilograms of corn starch were transferred into Bag Y?

	X	Y	Z
Before	3 u	4 u	1 u
Change 1	- 1.2 u	+ 1.2 u
Change 2		+ 0.9 u	- 0.9 u
After	1.8 u	6.1 u	0.1 u

Mass of corn starch transferred from Bag X into Bag Y
= 40% x 3 u
= ⁴⁰₁₀₀ x 3 u
= 1.8 u

Mass of corn starch transferred from Bag Z into Bag Y
= 90% x 1 u
= ⁹⁰₁₀₀ x 1 u
= 0.9 u

Mass of corn starch in Bag Y in the end
= 4 u + 1.2 u + 0.9 u
= 6.1 u

6.1 u = 30.5 

1 u = 30.5 ÷ 6.1 = 5

Mass of corn starch transferred into Bag Y
= 1.2 u + 0.9 u
= 2.1 u
= 2.1 x 5
= 10.5 kg

Answer(s): 10.5 kg