LIVING IN THE CITY
X = N: A “ONE-FITS-MANY” CITY “BALLPARK” ESTIMATE
Suppose the city population is Np million, and we wish to estimate N, the number of facilities, (dental offices, gas stations, restaurants, movie theaters, places of worship, etc.) in a city of that size. Furthermore, suppose that the average “rate per person” (visits per year, or per week, depending on context) is R, and that the facility is open on average H hours/day and caters for an average of C customers per hour. We shall also suppose there are D days per year. This may seem a little surprising at first sight: surely everyone knows that D = 365 when the year ...