The basic principles of mechanics, such as time and speed, are very common in almost any business analysis.
Public questions (free plan) are common interview questions. They are great for practicing, or if you want to filter candidates using the classic problems.
It takes Billy 4 hours to paint a fence by himself. It takes Suzy 6 hours to paint the same fence by herself.
How long will it take them if they start working on the same fence together and neither of them stops until the fence is completely painted?