It takes 9 minutes to paint 1 m^2 of wood. How long would it take to paint a wooden cube with sides of 2m?

The best way to think about this question is to imagine the plan of the cube. Looking at this you would see that there are 6 identical squares. Therefore you should realise that to work this question out you should work out the area of one square (4m²) and multiply it by 6 (4 x 6 =24).
If it takes 9 minutes to paint 1 m² of wood, painting 24m² would take 9 x 24 minutes, which equals 216 minutes. As there are 60 minutes in an hour, this would take 3 hours and 36 minutes.