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wu :: forums    riddles    microsoft (Moderators: ThudnBlunder, Grimbal, SMQ, william wu, towr, Eigenray, Icarus)    How many cars are there in the USA? « Previous topic | Next topic » Pages: 1 2 3  Reply Notify of replies Send Topic Print    Author  Topic: How many cars are there in the USA?  (Read 55262 times) Icarus wu::riddles Moderator Uberpuzzler Boldly going where even angels fear to tread.     Gender: Posts: 4863 Re: How many cars are there in the USA?   « Reply #25 on: Dec 10th, 2004, 11:14am » Quote Modify Since valid VINs are less than the total VINs, the percentage is less than 100. So, given the way you phrased that final line, you come up with less than 100 cars!   (By "valid", I assume you mean they already have been assigned to some automobile.)   I believe that what you meant was: take the ratio of valid VINs in your sample to the total size of the sample (not T). Multiply this ratio by T to estimate the total number of valid VINs.   But, if you can find that database of valid VINs, why not simply count its entries? Then you would have the exact number of valid VINs.   Also there is the question of just how closely the number of valid VINs matches the number of cars in the USA. Are VINs strictly for cars in the USA or are VINs an international means of identifying cars? If the latter is true, you are going to need to know what proportion of all cars are used in the USA. And if the former is true, then you need to know how many non-VIN cars are in the USA, and how many VIN cars are in other countries. Another problem with VINs: I, at least, interprete the question as refering only to cars that are still maintained. But a large number of vehicles have been scrapped since VINs were introduced. IP Logged "Pi goes on and on and on ... And e is just as cursed. I wonder: Which is larger When their digits are reversed? " - Anonymous John_Gaughan Uberpuzzler Behold, the power of cheese!     Gender: Posts: 767 Re: How many cars are there in the USA?   « Reply #26 on: Dec 10th, 2004, 1:43pm » Quote Modify Icarus,   The digits in the VIN each stand for various things. The first digit is the country of origin, where the final assembly occured. The next few identify the manufacturer and model. Then there are a few that are defined by the manufacturer, such as a serial number to identify otherwise identical cars, the year, engine type, etc. Usually the manufacturer reserves a digit for the target country of sale. They may combine countries, for example, I think most treat the U.S. and Canada as the same (this is why we have MPH and KPH on our spedometers). British models would have the driver's seat on the right side of the vehicle. Japanese cars might have other modifications. This is encoded in the VIN, but I believe it varies by manufacturer.   There are a few links that describe how to decode a VIN, but nothing I can get to through the firewall here at work. Try about.com or Wikipedia, I am sure one of them has more information.   In the end, this is still not 100% accurate. VINs repeat eventually, just like Socialist Security Numbers, and some people take cars into other countries after the dealer sells them. IP Logged x = (0x2B | ~0x2B) x == the_question The Trend Setter Guest Re: How many cars are there in the USA?   « Reply #27 on: Jan 14th, 2005, 10:41am » Quote Modify Remove There are 3. I counted them over the weekend. IP Logged Blazn Azn Guest Re: How many cars are there in the USA?   « Reply #28 on: Feb 8th, 2005, 5:53am » Quote Modify Remove theres 1 car in united states of AmeRiCa   rearranging the letters IP Logged nevin Guest Re: How many cars are there in the USA?   « Reply #29 on: Mar 13th, 2005, 11:16am » Quote Modify Remove I would agree with the whole VIN approach, in one way or another, but I think you could get a pretty good count by a combination of methods (assuming you have ACCESS to the information) to find the number of cars in the USA:   1) get dmv records for registered cars (or whatever you want). This would be the total number of cars at that instant registered and _legal_ 2) get shipping -> dealer records for the cars directly from the manufacturers (eg, GM, Ford, etc). This would count the cars that have been produced that you would be looking for, but not registered yet.   problem: "limbo" cars who have filed and are using their "temporary" registration certificate, unregistered (illegal) cars, exported/imported cars   SO, I would think that: a) arrive at the above counts through #1 and #2, then come up with a reasonable number for the "limbo" cars. Since you cannot legally drive the car, don't consider it a car 'legally'     b) OR consider that a car is a car is a car - get records from all car manufactures of ALL of the cars produced EVER and a listing of custom's declarations of shipping contents (assuming accurate) and count them all up. Even if the car has been smashed, pulverized, melted down, and resulted in recycled furniture, it's still a car....   ack...there has got to be some way.... IP Logged Car Manufacturer Guest Re: How many cars are there in the USA?   « Reply #30 on: Sep 4th, 2005, 11:33am » Quote Modify Remove The simple ans with generalized formulae can be:   Total no of cars in USA = No of Cars Manufactured in USA till date - no of Cars exported + no of cars imported   IP Logged towr wu::riddles Moderator Uberpuzzler Some people are average, some are just mean.     Gender: Posts: 13730 Re: How many cars are there in the USA?   « Reply #31 on: Sep 4th, 2005, 1:40pm » Quote Modify on Sep 4th, 2005, 11:33am, Car Manufacturer wrote: The simple ans with generalized formulae can be:   Total no of cars in USA = No of Cars Manufactured in USA till date - no of Cars exported + no of cars imported   minus the number of cars scrapped.. IP Logged Wikipedia, Google, Mathworld, Integer sequence DB Mateo Guest Re: How many cars are there in the USA?   « Reply #32 on: Sep 19th, 2005, 4:29pm » Quote Modify Remove Anyway, does any one know what  you call the number of cars a country has   is it automobile park or automotor Park.   any economist around? IP Logged cheapwhyskey Guest Re: How many cars are there in the USA?   « Reply #33 on: Oct 17th, 2005, 11:25pm » Quote Modify Remove   roughly equal to the number of liscense plates in the   us,  which would be no greater the maxium "number" possible on a plate (this number varies state by state) * the number of states.  which at the time of this post was still 50. IP Logged EasyRiter Guest Re: How many cars are there in the USA?   « Reply #34 on: Oct 23rd, 2005, 2:31am » Quote Modify Remove I think it's important not to think in circles. If we have average number of cars per household, then someone actually calculated in one way or another the number of cars before.     I think it's better to state how one would compute it: for example, we know how many barrels of oil are sold on the stock exchange each day and we know average gas expenditure. Weighing how many miles average car drives a day we can come up with a reasonable estimate. IP Logged ozkar Guest Re: How many cars are there in the USA?   « Reply #35 on: Nov 13th, 2005, 10:30am » Quote Modify Remove The answers for these questions are never exact. It is the approach you take what is important. To answer this question, I would say.     x = about 300 million people in USA   y=  about 5 people per family   c =about 1.5 cars per family   t =total cars     t = (x/y) * c   t - 90millions cars (using those numbers   IP Logged warden Guest Re: How many cars are there in the USA?   « Reply #36 on: Dec 14th, 2005, 3:35am » Quote Modify Remove many cars are not individually owned, but owned by dealers, rental car fleets, government, etc. IP Logged wsj Guest Re: How many cars are there in the USA?   « Reply #37 on: Dec 15th, 2005, 1:38am » Quote Modify Remove This can be estimated as assuming population of US as 300 million and a family unit of say 3, as 100 million family units. Say 60% of the family units have cars. That gives us 60 million units. Of the rest 200 million people ( assuming that 1 car per person in a family being there already and the  main bread earner would already be having/using the car) say again 30% owns a car, that gives us 60 million units. Now since business units also own cars. We have 5 million large and medium sized business. and 15 million very small business,self employed (US economic census). Assuming 10 vehicles per medium sized business and 1 per small one. Thats another 65 million business. So total comes around 185 million cars.     Another way to go about it could be through personal income basis.     Suggest if i am wrong.   Regards IP Logged inderaj Guest Re: How many cars are there in the USA?   « Reply #38 on: Dec 28th, 2005, 2:31pm » Quote Modify Remove Well, we have no context, but if we assume a context like: 1) Making a product for cars - market size 2) Deciding what size VIN to use 3) Deciding how long plates will be if all had US plates instead of state ones.   For all probable uses, 10-100 million might be good enough an estimate.   You should be able to work with reasonable estimates. IP Logged dshafranov Newbie     Gender: Posts: 2 Re: How many cars are there in the USA?   « Reply #39 on: Jan 19th, 2006, 5:47pm » Quote Modify Hi. I actually received this problem at Microsoft interview. While there are thousands of possible answers to this problem such as checking DMV records, examining VIN numbers, and etc, most of them are fairly unrealistic and will not be accepted (I know it for a fact because I tried). The interviewer will simply tell you that this information is unavailable and ask you to try a different approach. An "improved" answer would be to use the total number people in the US (known statistic) and divide it by average number of cars per person (unknown estimate) or to estimate the number of cars per town and to extrapolate the total across US, but these won't get by either. An "acceptable" solution involves using the total amount of petroleum imported into US, and then estimated the number of cars from that. Oh, and by the way, the interviewer will ask you to come up with an estimate, so be prepared to do some basic algebra.    Some of the variations of the problem that I have heard include:   * How many gas stations are there in the US?   * How many manholes are there in the US? IP Logged rajeevrla Newbie     Gender: Posts: 1 Re: How many cars are there in the USA?   « Reply #40 on: Mar 18th, 2006, 2:33pm » Quote Modify COUNTABLY INFINITE .Since you can put all the cars in one-to-one correspondence with the Integers .   This  is a term in mathematics and is most widely used in computer science as well. Countably infinite is mainly  used in Automata Theory.Since Alan Turing has done a really significant job in Theoretical Computer Science,right from giving us Turing machines and many more, he can no doubt be called as "Father of Computer Science ".   As computer science student Microsoft expects some logical reasoning behind ur answer. Now after giving the answer as countably infinite you can co-relate the no. of cars in USA and it's one-to- one correspondence with the integers . Then u can explain something about Countably Infinite and it's use in Computer Science.In this way u can really impress the interviewer. IP Logged Icarus wu::riddles Moderator Uberpuzzler Boldly going where even angels fear to tread.     Gender: Posts: 4863 Re: How many cars are there in the USA?   « Reply #41 on: Mar 18th, 2006, 5:06pm » Quote Modify I don't see how the interviewer is going to be impressed by your inability to count!   HOW in the world do you have a one-to-one correspondence between the obviously finite set of cars in the US and the infinite set of integers? IP Logged "Pi goes on and on and on ... And e is just as cursed. I wonder: Which is larger When their digits are reversed? " - Anonymous cwolves Newbie     Posts: 41 Re: How many cars are there in the USA?   « Reply #42 on: Apr 8th, 2006, 9:05pm » Quote Modify You're all assuming the question is asking:   "How many working cars are in America?"   It's not.  There are 300 Million people (give or take) in the USA.  Maybe 80 Million or so of these people are under 16 and can't drive.     220 Million left.   Average it out to maybe one working car per .7 people left (70% own one car).   154 Million left.   Assume an average age of maybe 45 years for everyone left and assume that a car last 15 years.  This means that on average everyone is on their 3rd car:   462 Million cars, 154 Million of these working.   Half of the "dead" ones have been destroyed, the others are either in junk yards or show cars, etc:   308 Million cars. IP Logged Grimbal wu::riddles Moderator Uberpuzzler     Gender: Posts: 7526 Re: How many cars are there in the USA?   « Reply #43 on: Apr 10th, 2006, 2:32pm » Quote Modify I recently saw a documentary about biofuel in Brazil. It said they have 1 car for 4 people.  Assuming a similar radio for the US would put the figure at 50 to 100 milion cars. IP Logged Icarus wu::riddles Moderator Uberpuzzler Boldly going where even angels fear to tread.     Gender: Posts: 4863 Re: How many cars are there in the USA?   « Reply #44 on: Apr 10th, 2006, 4:19pm » Quote Modify With all due respect to our Brazilian friends, the US has the highest per capita income of the world. Brazil has signficantly less. And the Brazilians do not have America's love affair with the automobile. I believe that the US has a significantly higher ratio of cars to people. Even if the cars have similar radios. IP Logged "Pi goes on and on and on ... And e is just as cursed. I wonder: Which is larger When their digits are reversed? " - Anonymous Grimbal wu::riddles Moderator Uberpuzzler     Gender: Posts: 7526 Re: How many cars are there in the USA?   « Reply #45 on: Apr 12th, 2006, 2:37pm » Quote Modify Actually, I would gladly go up to 1 for 2, or maybe 2 for 3, but I have trouble imagining that it is 1 to 1, considering that part of the population is too young, not able to drive or can not afford a car. But well, I have never been there, so what do I know? IP Logged Icarus wu::riddles Moderator Uberpuzzler Boldly going where even angels fear to tread.     Gender: Posts: 4863 Re: How many cars are there in the USA?   « Reply #46 on: Apr 12th, 2006, 6:00pm » Quote Modify 1:2 is probably too high. 2:3 certainly is. But 1:3 may be on the low side for the U.S. I know several people who have more cars than people in their households, even though that is the exception (as a matter of fact, right now I do, but only temporarily). IP Logged "Pi goes on and on and on ... And e is just as cursed. I wonder: Which is larger When their digits are reversed? " - Anonymous cwolves Newbie     Posts: 41 Re: How many cars are there in the USA?   « Reply #47 on: Apr 14th, 2006, 8:34am » Quote Modify 1:2 may be fairly close to the number of cars that your average person OWNS.  This doesn't say how many cars are in the country though!   You have to take into account the millions of cars sitting at car dealerships, junkyards, etc.  The several thousand people that own hundreds of cars because they're collectors, cars in museums, etc.   All told I wouldn't be surprise if there were more cars in the USA than there were people.  The vast majority of this number probably coming from cars in junkyards.   I still consider it to be a car until it is crushed into a little cube or stripped into thousands of pieces - most cars aren't. IP Logged Grimbal wu::riddles Moderator Uberpuzzler     Gender: Posts: 7526 Re: How many cars are there in the USA?   « Reply #48 on: Apr 15th, 2006, 8:36am » Quote Modify on Apr 14th, 2006, 8:34am, cwolves wrote: I still consider it to be a car until it is crushed into a little cube or stripped into thousands of pieces - most cars aren't. That brings the question of what is meant by "car".   The important is not whether the answer is strictly speaking correct, but whether it is useful.  If the figure is needed to compute the potential market for car insurances or GPSs, what is meant is probably cars that are functional and in service.  I can't imagine why anybody would want to know how many cars inclusive wrecks there are in the US.   It is probably something the interviewer wants to test, whether you make sure to understand what he means by "car", and not just assume that your own understandin of the word is what is asked, and that the interviewer should have been more specific if he meant somethin else. IP Logged thepps Newbie     Gender: Posts: 1 Re: How many cars are there in the USA?   « Reply #49 on: Sep 18th, 2006, 5:04am » Quote Modify =>How many cars are there in the USA =>A lot =>Still A guess... =>If a car's number plate is like that BP 337 BZ then the total number is surely less than   264 X 103.   Obviously much less than this number as all characters will not be allowed. Or you can get a list of all lisence numbers issued till now in states. I guess they maintain database. 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