6. Three rules:
1. State your assumptions
2. Justify your guesses
3. Be “dimensionally consistent”
7. Population of Chicago: ~5,000,000
Households: 5,000,000 / 2 people ≈ 2,500,000
Pianos: 5% of households ≈ 125,000 pianos
Assume: each piano tuned once a year, taking
~2 hours: => ~250,000 piano-tuning hours
=> 250,000/8 hours per tuning day ≈ 30,000 days
200 working days a year => around 150 tuners
12. How many papers are sold a year?
225m people (aged 20-80)
so around ~100m households
maybe 25% buy a paper?
=> 25m daily circulation
~400 days a year, so 10bn a year
13. How much revenue per copy?
Sales revenue: ~$0, more or less
Revenue from ads ≈
revenue per ad x number of ads
≈ 2¢ x 100
≈ $2 per copy
14. So total US newspaper industry:
≈ 10bn papers x $2/paper
≈ $20bn per annum!
16. Online:
200m working adults
200 working days per year
4 pages each
4 ads a page
$5 cpm per ad = 0.5¢ per view
=> 200m x 200 x 4 x 4 x 0.005
≈$3.2bn online ad revenue