Description

How many piano tuners are there in New York City?

Solution

1. Roughly how many people live in New York City? — 8,000,000

2. Does every person own a piano? — no

3. Can we assume that families own pianos, not individuals? — yes

4. How large is the average family? — 5 people

5. So how many families are there in NYC? — 1,600,000

6. Does every family own a piano? — no… perhaps one in ten does

7. So how many pianos are there in NYC? — 160,000

8. How often per year do pianos need to be tuned? — once per year

9. How many piano tunings can one piano tuner do? — let’s say 4 per day, so if there’s 200 working days in a year, that’s 800 per year

10. So how many piano tuners could NYC support?— 160,000/800 = 200 piano tuners