Question

Wilson paints 40% of a bookcase in 20 minutes.

How much more time will it take him to finish the bookcase?

Answer 1

30 minutes

Explanation:

The percentage rises up by 40% every 20 minutes and if we divide that in half he paints 20% in 10 minutes. Wilson needs to paint 60% more of the bookcase. 40% plus 20% is 60%. So we just add 20 with 10 to get 30 minutes.