Two identical pails A and B contained some water. Pail A was ¹₆ filled and Pail B was ¹₇ filled. The ratio of the total mass of Pail A and the water in it to the total mass of Pail B and the water in it was 11 : 10. The total mass of the two pails and the water they contained was 3150 g. What is the mass of an empty pail?
Mass of Pail A and the water inside = 11 u
Mass of Pail B and the water inside = 10 u

Total mass of the two pails and the water inside them
= 11 u + 10 u
= 21 u

21 u = 3150

1 u = 3150 ÷ 21 = 150

Mass of Pail A and the water in it more than mass of Pail B and the water in it 
= 11 u - 10 u
= 1 u

Fraction of the water that Pail A had more than Pail B 
= ¹₆ - ¹₇
= ⁷₄₂ - ⁶₄₂
= ¹₄₂ 

¹₄₂ of the water capacity → 1 u
⁶₄₂ of the water capacity → 6 x 1 u = 6 u

Mass of an empty pail
= 10 u - 6 u
= 4 u
= 4 x 150
= 600 g

Answer(s): 600 g