Cost Models (cont)
Our cost models are "rough" (based on assumptions)
But do give an O(x) feel for how expensive operations are.
Example "rough" estimation: how many piano tuners in Sydney?
- Sydney has ≅ 4 000 000 people
- Average household size ≅ 3 ∴ 1 300 000 households
- Let's say that 1 in 10 households owns a piano
- Therefore there are ≅ 130 000 pianos
- Say people get their piano tuned every 2 years (on average)
- Say a tuner can do 2/day, 250 working-days/year
- Therefore 1 tuner can do 500 pianos per year
- Therefore Sydney would need ≅ 130000/2/500 = 130 tuners
Actual number of tuners in Yellow Pages = 120
Example borrowed from Alan Fekete at Sydney University.
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