1. estimate the number of barber shop in your city
https://www.jianshu.com/p/1431daad2c62
The core of this way of thinking, is to explore the results you want to use a mathematical formula to show it. How are we beginning with a pancake stalls example of view? You should use: Profit = Revenue - variable costs, while revenue = customer unit * * flow conversion rate, the number of pancakes * = variable costs per unit cost ....... And so on, step by step dismantling each variable, you can get the final result.
case analysis
Also, this way it can take advantage of this question on the number of computing Xiamen City barber shop
In the beginning, my first thought is to cover the average density of the total area of Xiamen / barber shop to calculate, but due to severe uneven economic development in Xiamen City, the average density of data If I had to guess, probably there will be more large errors, so in the end I decided to adopt the perspective of supply and demand to solve this problem. From an economic point of view, a larger market segment if there are no other variables appear in the long-term competitiveness, all corporate profits will tend to 0, and ultimately achieve a dynamic equilibrium. Under this assumption, supply and demand will be basically balanced. So I set out a list of the underlying formula from the demand side: Xiamen City, the number of barber shop = total number of people in barber / average number of years of service for each barber shop.
Let the dismantling of these two segments concepts: the average number of years of service total number of members of the public and each barber barber shop years. The total number of people in the barber haircut male population * = male + female barber in the barber number of years the number of female population * barber, barber shop every annual average number of service = average number of single barber shop barber * Number of units * 365 day service.
Further split the total number of members of the public haircut. I remember before seen somewhere over a data: about 500 million people in Xiamen City resident population, and remove those who no consumer demand Barber (who do not need to go to the barber shop haircut) one-fifth of such bald, long hair long who, monks and nuns, parents and children OEM slow hair growth or on behalf of the children of the elderly scissors and so on, it can be said that there were 400 million people have a haircut consumer demand. According to the gender distribution of natural population point of view, combined with industry characteristics Xiamen, Xiamen City as a whole can be considered sex ratio is more natural state, it can be 50-50, a male barber consumer demand of 200 million people, 200 million women. According to my daily experience, men's hair more frequently than women, men are generally hair cut once a month, 12 times a year and therefore Barber; while women about three months for a haircut, the barber four times a year. Therefore, we can calculate the Xiamen City, the total number of people in the barber = 2000000 * 2000000 * 12 + 4, results for 32000000, which is thirty-two million times haircut needs, male to female ratio of 3: 1.
We further split the average number of years of service for each barber shop. First look at our previous formula: Each barber shop in the average number of service = average number of single barber shop barber day service * Number of units * 365. According to experience, I would single barber shop is defined as the average number of 3 people. Although relatively prosperous compared to where I Siming, the three people some less, but in fact, accounted for a much larger body mass base of the pyramid of small and medium barber shop may be one or two barbers, therefore defined as the average number 3 people may have suspected there may be enlarged. The next day is the unit number of barber service. The number of units barber work day = day service / customer service unit of time, this appeared different service men and women a matter of time, in my experience, men haircuts time is usually shorter than women. Here we will be male barber time is defined as the average of 30 minutes, the female barber (hair included) time is defined as an average of 40 minutes. Previously referred to female ratio was 3: 1, so according to gender after weighted average of the time required for each customer 32.5 minutes, i.e. 0.542 hours. According to the time and I chatted in the barber haircut brother and learned that they work every day time in about 10 hours. The above data, you can calculate the number of units Hairdressers day service = 10 / 0.542, the result is 18.45 times, that is, each day the number of barber service is about 18.45 times, of course, it is undeniable that the barber fact, there are busy periods of the points, we are here for simplicity, according to my knowledge a rough estimate. Further can calculate the average number of services per barber shop in = 3 * 18.45 * 365, the result is 20,202.952 people.
Preparatory work basically completed, let us return to the beginning of the underlying formula: Xiamen City, the number of barber shop = total number of people in barber / average number of years of service for each barber shop. We have calculated: the total number of people in the barber = 32000000 times, and each barber shop in the average number of service = 20202.952 times, the former divided by the latter, you can get the number of Xiamen City barber shop is 32000000 / 20202.952 = 1583.92694, or about to 1600! We're done!
In order to verify the accuracy of the results of my calculations, my Internet search, relevant data, but unfortunately did not search to related statistics.
The real problem
Perhaps you have a question? What is the purpose of this calculation? Why big companies love to visit this kind of problem?
In fact, the results of these questions is how much is not very important, important is the idea, because the ability to solve these problems is a concentrated expression of a person careful thinking and common sense Reserve (the degree of concern of daily life), and the ability of these two points together, the future is a person analysis and problem-solving potential at work. If the thought is not careful, it is difficult to split a large, complex problems in a short interview to a series of small issues; but reserves are not enough common sense, not only difficult to physics and chemistry logical split, even if successful split , it is difficult for each data more reasonable assignment, may eventually arrive at a ridiculously data. If I calculated the number of Xiamen City barber shop is 200 000, the data reasonable? A second-tier cities to a mere 5 million people, the answer is naturally negative.
Daily use
Of course, this way of thinking can be applied not only in the nature of our future interview, in fact, it is in life there are a wide range of uses. Problems are almost always complex problems we face in everyday life, then many large life if we will be dismantling a complex issue, and finally get one small problem can be directly assigned, that is capable of being directly addressed, the problem can be solved, and we can be more targeted in the process of problem-solving, want to avoid is a one, eyebrows and beard grabbed.
Finally, it gives you a thinking questions, please estimate the annual profit in your cell door convenience stores, with the use of this way of thinking, you will benefit from the infinite.
2. estimate put the amount of shared bicycle and a city daily number of transactions
Links: https://www.nowcoder.com/questionTerminal/562cee797e25429eb12dcb73dd935f44?orderByHotValue=0&mutiTagIds=763&page=1&onlyReference=false
Source: Cattle-off network
link: https: //www.zhihu.com/question/20212434/answer/240281295
Source: know almost
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This sizing problem can be said to be a classic case interview questions. I was in Shanghai, to Shanghai to measure digital good.
Given the sense of life, a taxi is less than the demand (otherwise there will not be traveling a bit), so this measure from the supply side.
Ideas are as follows:
Shanghai taxi-age population *% *% * have a license to work in the private sector to work in proportion% *% * in proportion taxi company taxi company drivers do *% (the average number of taxi drivers)
Among them, the proportion of work in the taxi company has split into male and female: the taxi company to work ratio = (% * men at work probability taxi company%) + (F% *% probability to work in the taxi company)
Next, enter the number of beats links:
Shanghai Population = 25 million
Average life expectancy of about 80 years of age, a taxi driver in 20-60 years, that is 50%
Have a license% = 40%
In private working ratio% = 60%
Male: female = 50%: 50%
Men in the possibility of taxi work: the possibility of 3% of women working in the taxi: 1%
In the taxi companies do drivers% = 80%
Each driver has two-thirds of the car (some taxi companies will be in the form of two shifts to maximize the utilization of the taxi)
The results calculated is 32000.
Finally, check the number of taxis at the Shanghai is 40000.
Also, according to the other already Tieshanglai answers, from the time the car can be started.
Shanghai Population Age% * revenue * car * taxi dynamic range%% * (1 private car does not need to consider the alternative%) * Weekly taxi ride time * 1 / (every taxi operators week time * average number of passengers per vehicle) = 2016, the number of taxis.
Beats:
Ride ages (15-65): 60%
Income: 80%
Taxi dynamic range: 80%
There need not consider the alternative of private cars%: 30%
Weekly taxi time: 1 hour
Taxi hours of operation per week: 16 hours / car * 7 days / week = 112 hours
The average number of passengers per vehicle: 1.5 persons / times
The final result is calculated 40000.
In fact, you can also do a sanity check: Shanghai each district about how a small car?
40K / 18 is approximately equal to 2222 / region, reasonable.