this paint can holds 2.5 litres with a height of 20cm work out the radius of the can

2.5 litres = 1,000 * 2.5 = 2,500 cubic cm

volume = π * radius^{2} * height

2,500 = π * r^{2} * 20

\(\frac{2,500}{20\pi}=r^2 \\~\\ \sqrt{\frac{2,500}{20\pi}}=r \\~\\ 6.307 \approx r\)

That should be 6.307 centimeters, sorry I meant to put that!