?
Sam takes 20 days to build a wall.
Taylor and Kelly each take 10 days to build a wall.
How long will it take the three of them to build a wall if they work together?
Puzzle Copyright © Kevin Stone
workings hint hide answer print
Share link – www.brainbashers.com
Answer
4 days.
Reasoning
In one day Sam can build 1/20 of a wall, Taylor and Kelly can each build 1/10.
So in one day, in total, they can build 1/20 + 1/10 + 1/10 = 1/4.
Therefore the wall will take 4 days to build.
Note: BrainBashers has a Dark Mode option – I recommend not using your browser's dark mode or extensions for BrainBashers