Clarify

=========

1) First clear with interviewer about Network City or State

Equation

========

No of people with dental problem per month / No of patients attended by dentist per month

Break down

==========

1. No of patients attended by dentist per month (160)
   • Usually Dentist Works 8 hours a day and 20 days per month
   • Dentist spends avg 1 hours per patient
   • Total patients attended per day 8
   • One dentist can attend 160 patients per month ( 20 X 8)
2. No of people with dental problem per month
   • Consider NY population as 10 M
   • Divide the population in age group
     • 0 – 10 years – 10% – 1M
     • 10 – 30 years – 30% – 3 M
     • 30-60 Years – 40% – 4 M
     • 60 & Above years –  20% – 2M
   • Define the dental problem ration per age group in year
     • 0-10 Years – 10% -> 10% of 1M – 100K
     • 10-30 Years – 20% -> 20% of 3M – 600K
     • 30-60 Years – 30% -> 30% of 4M – 240K
     • 60 & Above years -> 40% – 40% of 2M – 800K
   • Total people with dental problem through out the year – ~1.7 M
   • Total People with Dental Problem in month – ~89K 

Total Dentist required = 89K / 160 = 5562

How many dentists are there in NY:

Population of NY is approximately 8.2M

Based on my visits to several dentists – they see approximately 10 patients each day and patients normally see dentists at least twice a year.

In 1 month, a dentist approximately works 20 days a month (working flexible hours) seeing 10 patients each day.
Therefore in 6 months – they see 6 * 20 * 10 = 1200 patients
After 6 months, lets assume that the same patients start repeating.

If 1 dentist can serve 1200 patients in 6 months
Then for 8.2 M patients in 6 months, we need = 8200000/1200 = 6833 dentists = approximately 7000 dentists

Since there are patients that probably need more visits (children, adults with serious dental issues)- this number can be increased by 30% to be 9100 dentists.

I like to answer estimation questions like this by starting with a basic equation. Here’s an example:

Number of Dentist in New York = eligible population who visit dentist/ number of patient-dentist treats every year

Assumption and Facts:

1. Population of New York = 8 million (fact)
2. Dentist spend on average 2 hrs per patient (assumptions)
3. Dentist works 8 hours per day for 5 days ; 40 working hours per week (assumptions)
4. 85% of 8 million are in the age bracket 5 to 85 who visit dentist for consultation, routine checkup, surgery etc. = 6.8 million (assumptions)
5. People visit dentist twice per year (assumptions)

Number of patient dentist treats every week = 40 hours per week working time / 2 hours per patient

= 40 / 2

= 20 patient per week

Number of patient dentist treats in a year = 20 * 52 weeks per year

= 1040 patients per dentist