When my finance students ask me to describe the right way to answer a question, I always remember an apocryphal story about a physics student at the University of Copenhagen who once faced the following challenge: Describe how to determine the height of a skyscraper using a barometer. The student replied:

— Tie a long piece of string to the barometer, lower it from the roof of the skyscraper to the ground. The length of the string plus the length of the barometer will equal the height of the building.

The enraged examiner demanded that the student give the right answer, the answer that displayed the knowledge of physics. The student said:

— Well,

1) You could take a barometer up to the roof of the skyscraper, drop it over the edge, and measure the time it takes to reach the ground, but too bad for the barometer.

2) If the sun is shining, you could measure the height of the barometer, then set it on end and measure the length of its shadow. Then you measure the length of the skyscraper's shadow, and after that, it is a simple matter of proportional arithmetic.

3) If you wanted to be highly scientific, you could tie a short piece of string to the barometer and swing it as a pendulum, first at ground level, then on the roof of the skyscraper. The height of the building derives from the difference in the pendulum's period.

4) If the skyscraper has an outside emergency staircase, it would be easy to walk up and mark off the height in barometer lengths.

5) If you wanted to be boring and orthodox, of course, you could use the barometer to measure the air pressure on the roof of the skyscraper and on the ground and convert the difference into a height of air.

6) But since we continually strive to seek new ways of doing things, probably the best way would be to knock on the janitor's door and say: If you would like a nice new barometer, I will give you this one if you tell me the height of this building.

This student was Niels Bohr.

Mastery is not moored to the single right answer.