Three groups of people were given £50 or dollars whatever your choice! and ask to work out how tall a particular building was.
The groups were, mathematicians, scientists and engineers.
The mathematicians got a tape measure a plumb bomb and a set square and triangulated the height of the building.
The scientists got some ball bearings and stop watches and timed how long it took for them to hit the ground to calculate the height of the building,
When they finished they came together and compared results, looking around for the engineers they were nowhere to be seen. they thought they must still be working and as they had some money left they decided to go to the pub/bar.
when they get to the pub they find the engineers there already well on their way to being drunk, so they confront them. "You haven't done any work at all have you? you just spent all the money in the pub?"
to which one of them replies, "Oh no, burp..!" "I gave the janitor a fiver and asked him how tall the building was!"