A “Fermi problem or question” is a question which seeks a quick, close estimate,

A “Fermi problem or question” is a question which seeks a quick, close estimate, which is either difficult or impossible to measure without complicated calculations. It is [answered] based “upon understanding of the world, upon everyday experience, and upon the ability to make rough approximations, inspired guesses, and statistical estimates from very little data” (Philip Morrison, 1963).
Here is a good explanation with examples: https://en.wikipedia.org/wiki/Fermi_problem (Links to an external site.)
Example: Estimate the number of steps you would take to complete the Appalachian Trail. (Note: In your work, the more steps you show in solving the problem, the more credit you can earn, even if your estimate is too far off).
Establish some sensible limits: 1, 10, or 100 miles is too short (the trail crosses several eastern seaboard states); 10,000 or 100,000 is too long (the circumference of Earth is about 25,000 miles).
Make a sensible estimate of the trail in miles based on your limits: About 2,000 miles.
Estimate an average step length (2 feet).
Estimate how many steps there are in a mile: About 2,500 steps per mile.
Multiply the number of miles by the number of steps per mile to determine the number of steps: 5 million steps.
Check your answer using Google: 2,200 miles for the Appalachian Trial, 5,380 feet per mile, and 2.2 feet per step. (2,200 x 5,380) / 2.2 = 5.38 million steps
For this Week 3 calculation assignment, carry out the following Fermi problems and check your answers using Google once you complete your calculations. Comment on how accurate your answers are and what you could do to get a more accurate answer for the Fermi problems. You will have to do some internet research to find factual information to back up your calculation. For example, how many kilos does an average person eat a day, when looking at how much food you would need for a trip to Mars? You need to include your reasoning and the steps you take to get to an answer like the example above.
Question 1: Estimate the mass of food and water that a team of six astronauts would need for a standard two-year mission to Mars. (Note: the two years includes the round trip.)
Question 2: Estimate how long it would take to drive from Los Angeles to New York City.
Question 3: Estimate the number of apples produced per year by a mature honey crisp apple tree.