Two! one to change the light bulb and the other to rotate the universe!
None. They just move out of the house.
None, because they can't climb the ladder.
None. They aren't about to change a bulb when flipping a switch has worked for 15 years.
One. They're efficient and don't have humour.
The mathematician says "2" The Physicist says "2, plus or minus 0.1" The engineer says "Probably around 2, but let's say 3 to be on the safe side".
Nevermind, it doesn't really matter.
Professor: Astronomical.
I Have Read and Agree to the Terms of Service."
Interviewer:"If the Earth rotates 30 times faster, what will happen?" engineer:"We will get our salary everyday" :D Think Greedily Act Confidently
Two, one to hold the bulb and one to rotate the universe.