Estimation Techniques and Order of Magnitude Problems

One of the more useful skills that you can gain is to become adept and order of magnitude estimation (you will amaze your friends and maybe even win money from them ...:) )

Today we will try a bunch of practice problems to hone our skills.

The basic rule set for doing an estimation problem is

• Understand the problem and what is being asked

• choose a set of consitent units

• try to scale up a local example that your familiar with

• devise an estimation plan

• turn the crank on your plan

• peform a reality check on your result

In the problems that follow, we will be using our new interface for publishing results. So

Click here to launch the interface to report your values

To begin with, I will work out on the board the procedure for estimating the number of grains of sand on all the world's beaches. This will give you an example of how to approach these problems.

Estimation questions: (some of these are easy, some are very hard) No fair Googling for the answers in class!

The goal of this exercise is to compare answers and methodologies for arriving at these various estimates.

1. How many McDonald's restauraunts are there in the US.?

   
   

2. If you make 20$ per hour, what is your annual income?

   
   

3. How many gas stations are there in the US?

4. How many animals are slaughtered in the US annually for food production? Your estimate is for mammals and fowl only, not fish.

5. How many lbs of batteries are available for sale in retail stores in the whole US?

6. How many Douglas Fir Trees are there in Oregon (this one is very hard)?

7. How many gallons of water are used annually for washing clothes in the US?

8. How many artillery shells did Russia fire into Berlin during the last 10 days of WWII?

9. How many K12 schools are there in the US?

10. How many Lawyers are there in the US?

11. How many gallons of gas are annually used in the US?

12. How many cell phones are there in the US?

13. How many rats live in New York City?

14. How many gallons of soft drinks does the typical person in the US drink in one year?