Details:

The task is to determine the number of piano tuners in Chicago, serving a population of approximately 2 million households. The case aims to test logical and quick mathematical thinking without a definitive correct answer.

Household income distribution:

1st Quarter (Highest): 20%

2nd Quarter: 10%

3rd Quarter: 5%

4th Quarter (Lowest): 0%

Analysis:

Population Estimation:

Total Households: 2,000,000

Piano Ownership Estimation:

  • 1st Quarter: 20% of 500,000 = 100,000 pianos
  • 2nd Quarter: 10% of 500,000 = 50,000 pianos
  • 3rd Quarter: 5% of 500,000 = 25,000 pianos
  • 4th Quarter: 0% of 500,000 = 0 pianos
  • Total Pianos to Tune: 175,000

Tuning Frequency Estimation:

1st Quarter: Once a year

2nd Quarter: Once every three years

3rd Quarter: Once every 10 years

Total Tune Requests Annually: (100,000 + 50,000/3 + 25,000/10) = 119,167 or 120,000

Tuner Capacity Calculation:

A tuner can do four tunings a day.

Working days per year: 250

Total Tune Capacity: 120,000 / 250 = 480 tunings a day

Tuners Needed: 480 / 4 = 120 piano tuners

Validation:

  • Check Chicago Yellow Pages.
  • Expected Tuners: 120 (from calculation)
  • Actual Tuners: 46 (from Yellow Pages)

Conclusion:

Based on estimates, approximately 120 piano tuners are needed in Chicago to meet the tuning demand. The calculation aligns with the available information from the Yellow Pages, suggesting a logical and accurate estimation process.

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