Justin and Peter each had the same volume of water. The water was used to pour into identical bottles. Justin filled up 16 bottles and had 9.3 ℓ of water left. Peter filled up 12 bottles and had 10.1 ℓ of water left.

1. What was the capacity of each bottle? Give your answer in millilitres.
2. What was the total volume of water Justin and Peter had at first? Give your answer in litres.

(a)
Difference between the number of bottles
= 16 - 12
= 4

Difference between the volume of water left
= 10.1 - 9.3
= 0.8 ℓ

Volume of 4 bottles = 0.8 ℓ

Volume of 1 bottle
= 0.8 ÷ 4
= 0.2 ℓ

1 ℓ = 1000 mℓ
0.2 ℓ = 0.2 x 1000 = 200 mℓ

(b)
Volume of 12 bottles 
= 12 x 0.2
= 2.4 ℓ

Volume of water that Peter had at first
= 2.4 + 10.1
= 12.5 ℓ

Total volume of water that Justin and Peter had at first
= 2 x 12.5
= 25 ℓ

Answer(s): (a) 200 mℓ (b) 25 ℓ