Determine if the following ratio form a proportion
39 litres : 65 litres :: 6 bottles : 10 bottles

The correct answer is Yes

39 litres : 65 litres :: 6 bottles : 10 bottles

⇒ 39 litres : 65 litres = $\dfrac{39}{65}$ = $\dfrac{3}{5}$


6 bottles : 10 bottles

⇒ 6 bottles : 10 bottles = $\dfrac{6}{10}$ = $\dfrac{3}{5}$


∴ 39 litres : 65 litres :: 6 bottles : 10 bottles are in proportion.