how many restaurants are there in san francisco [Music] my name is ilana walder results i'm a former yahoo apm and in this exponent expert video i'll be answering the estimation question how many restaurants are there in san francisco so the first thing i want to clarify with this question is how we're defining restaurant and for the purposes of this video i'm going to assume that we mean places where people go out to sit down and eat in a meal so bakeries don't count coffee shops don't count and to go only places don't count so with that clarified i'm going to actually approach the estimation and i can think of two ways to do this one is population based and one is area based so i'm going to start by estimating with the population based method and then i'll use the area based method to sanity check my result so population based estimation well start with how many people there are in san francisco and we want to use round numbers whenever we can so i'm going to say 1 million i know it's probably a little less than that for the technical population of sf but there are tourists there are people nearby in the south bay in east bay who might venture over for dinner so let's call it a million next question is how often do these people eat out and my assumption would be that given that we're counting both lunch and dinner and that we've got a lot of young high earning professionals people are eating out pretty often i would say probably at least four to five meals a week between lunch and dinner and so my guess is going to be that on any given day of three quarters of the population eats one meal out that's 750 000 people going to restaurants so i'm going to start writing these numbers down as you should so we have one million population three quarters each out per day equals 750k eating out per day so now we need to know what the capacity of restaurants are and how many restaurants we would need to serve that many people eating out so when i think about a typical restaurant the typical table size is four you see a lot of tables of two but we also see a lot of larger parties so let's say tables of four and of course there are large medium and small restaurants but i would say the typical restaurant probably has 20 tables um so 20 tables of four and how often do they turn those tables in a day well it depends whether they're open for both lunch and dinner or just for dinner i know that typically a dinner restaurant is only going to be able to turn their tables twice and i don't think you typically turn your tables at all for lunch you're usually open for about two hours at lunchtime and you can only see one seating in that time and given that some restaurants are open for lunch and some aren't i'm gonna say you get 2. 5 turns on average so let's multiply that together to get the capacity tables of 4 with 2. 5 turns and 20 tables that's 20 times 4 times 2.
5 which equals 20 times 10 which equals 200. so the typical restaurant can serve 200 people per day and we have 750 000 people eating out per day so now we just need to divide 750 000 by 200 and i'm going to use a shortcut i'm going to divide 750 000 by 100 to give me 7500 and then i'm going to divide that by two to get me 3750.
