Question

An experienced housepainter can paint an inside wall in under twenty minutes. An inexperienced housepainter can take up to one hour. If a team of an experienced painter and an inexperienced painter work on a room together, what is the longest it should take them to paint the four walls, if they finish at the same time?

Answer 1

1 hour. The experienced painter will paint 3 walls (1 every 20 minutes) while the inexperienced painter will paint one wall in the hour.