MBA Strategy arrow MBA карьера arrow Study the Case. Типы вопросов кейсов. Part 2

Study the Case. Типы вопросов кейсов. Part 2

Продолжаем писатьо бизнес-кейсах, их примерах, а также способах их решения. В продолжение предыдущей статьи в данном материале приводим примеры такого типа вопросов в кейсах как «back-to-the-envelope» вопросы. Примеры, которые будут рассмотрены, с практичной точки зрения публикуются на английском языке.

How many gas stations are there in the U.S.? (Population question)

I live in a town with a population of 30,000. There are six gas stations serving our town. Therefore, I'll assume that each gas station serves about 5,000 customers. If the population of the U.S. is 300 million, I'll just divide 300 million by 5,000 and get 60,000 gas stations in the U.S.

If you tried to answer this question based on households or individuals you would quickly find yourself mired in numerous and unnecessary calculations.

How many garden hoses were sold in the U.S. last year? (Household question)

The population of the U.S. is 300 million people. The average U.S. household is made up of 3 people, so we are talking about 100 million households. (You always want to work with 100 million households in the US and 200 million in Europe.)

I'm going to estimate that 50 percent of the households are either suburban or rural. That makes 50 million households. I'll also assume that 20 percent of those homes are apartments or condos. That narrows us down to 40 million houses which most likely use a garden hose. Garden hoses are relatively inexpensive, so people are likely to have a hose in the front and a hose in the back yard. That makes 80 million hoses. I want to add in another 10 million hoses which can be found in nurseries, zoos, and other outdoor facilities like Fenway Park. Most of those businesses have at least two hoses.

We are now up to 90 million garden hoses.  Hoses aren't replaced every year. I'd say that they are replaced every 3 years unless they are run over by a lawn mower or run into the business end of a dog's tooth.  So we take 90 million hoses divide it by 3 and come up with 30 million garden hoses sold each year.

How many pairs of boxers are sold in the U.S. each year? (Individual question)

I'm going to start by stating some assumptions. I'm going to assume that the population of the U.S. is 300 million, that the life expectancy is 80 years, and that there are the same number of people in each age group (i.e., there is the exact same number of 3-year-olds as 73-year-olds). So if you divide 300 million by 80, you get a little over 3.75 million people per age group. We'll round it off to 4 million people. I will also assume a 50/50 split between men and women.

Children ages zero - three mostly wear diapers, and kids ages four - nine mainly wear jockey-style. So we'll focus on the ages between 10 and 80. That's 70 years to cover. I'm going to go out on a limb here and say that only 10% of females ages 10 to 30 own a pair of boxers and, of that group, each might buy one pair a year.

(2 million females x 20 years) x 10% = 4 million boxers.

Males between the ages of 10 and 20 wear them as a fashion statement, so I'll assume that 75% wear boxers and that they buy 3 pairs a year (the economical 3-pack).

(2 million males x 10 years) x 75% = 15 million boxers 15 million boxers x 3 pairs = 45 million boxers.

Of males between the ages of 21 and 80 (round off to 60 years), 50% wear boxers and buy or receive as birthday or holiday gifts 6 pairs (2 sets of 3-packs) a year.

(2 million males x 60 years) x 50% = 60 million males wearing boxers. 60 million x 6 pairs of boxers = 360 million pairs of boxers.

How much does a 747 weigh? ("Who thinks this stuff up?" question)

Your guess is as good as mine. Ask questions, then break down the elements, and make assumptions. Are there passengers on board? No. Any baggage? No. Are the fuel tanks full or empty? Full. Any food or beverages on board? No.

Now you just go ahead and calculate the weight of each part of the plane.

• 8 full fuel tanks: I'll assume the plane can fly 6,000 miles and uses 10 gallons to the mile. So that's 60,000 gallons at 2 pounds a gallon equals 120,000 pounds.
• 18 tires: I'll assume that the tires weigh 200 pounds each — that's 3,600 pounds.
• 4 engines: I'll assume 2,500 pounds each, which adds another 10,000 pounds.
• 2 wings: 200 feet long by 30 feet wide is 6,000 square feet, times a square foot weight of 5 pounds times 2 wings equals 60,000 pounds.
• Interior: 75 rows of seats times 4 feet per row equals 300 feet. Add on the cockpit, bathrooms, etc., let's say around 400 long. I assume that the average weight per foot is 10 pounds, which equals 4,000 pounds.
• The seats: They number, say 500, and weigh 10 pounds each, so that's 5,000 pounds.
• Air in the cabin: It's captured air so we need to add one ton for the air in the cabin — 2,000 pounds.
• The aluminum exterior: It's pretty thin and lightweight. If the plane is 400 feet long by 25 feet high, then about 10,000 exterior square feet at 1 pound per foot equals 10,000 pounds.
 Miscellaneous materials: The tail, overhead bins, carpet, stairs and bathroom fixtures add on, say, another 2,000 pounds.

Now you add up the pieces: 
120,000 + 3,600 + 10,000 + 60,000 + 4,000 + 5,000 + 2,000 + 2,000 + 10,000 = 216,000, or round up to 220,000 pounds, or 110 tons.

How many NetFlix DVDs get lost in the mail each year? (Household problem)

There are 300 million Americans. The average American household is made up of 3 people, thus there are 100 million American households. In order to order NetFlix you need access to the Internet and to own a DVD player. I'll assume that 50% of American households have both access to the Internet and a DVD player. That gives us 50 million households.

NetFlix was first to market with its service; however, consumers still like to go to the DVD store, they also have access to video on demand through their cable or satellite companies, and Blockbuster just entered the DVD by mail market - so I'll assume that 10% of the households have NetFlix. That means that NetFlix has 5 million subscribers.

Netflix has different service plans where consumers can rent anywhere from one to five DVDs at a time. However, I'll assume that the average NetFlix household rents 4 movies per month. Five million subscribers renting 4 movies a month equals 20 million DVDs a month or 240 million DVDs a year. Taking in to account that the DVD makes a round trip from NetFlix to my house and back again, I'll assume that 1 % of the DVD mailers get lost in the mail. Based on those assump¬tions I'd estimate that 2.4 million DVDs get lost in the mail each year.

Notes: I was conservative with my estimates. The advantage of this is that it keeps your numbers manageable. Otherwise I could be calculating in the billions. According to The Wall Sreet Journal (3/27/07), at the end of 2006 Netflix had 6.3 million subscribers renting 1.5 million DVDs a day.

Estimate the size of the bubble gum market in the U.S. (General population question)

First, I'm going to make a few assumptions. I'll assume that there are 280 million Americans and that the average life expectancy of an American is 80 years. I'm also going to assume that there is an even number of people in each age category. So, I divide 280 million by 80 and get 3.5 mil-lion people in each age group. To make things easier, I'm going to calculate assuming 50 weeks in a year.

AgesNo. People# that Chewpieces/ per weekpieces/ year
6-10 17.512m106b
11-15 17.512m2012b
Totals2B0m40m 20.85b

I'd also like to think about where bubble gum is sold. As I remember, bubble gum is sold in packs of 10 pieces in convenience stores, grocery stores, newsstands, etc. You can also find bubble gum inside baseball trading cards and gumball machines.

I'm going to break the population down into different age categories, estimate the number of people who chew bubble gum in each age group, and the number of pieces they chew each week and convert that into an annual number. Let's make a chart.

So I'm going to say that 20 billion pieces of bubble gum are sold each year. Ten pieces per pack equals 2 billion packs, at 50 cents a pack, equals $1 billion.

How many ATMs are there in the country? (Population problem)

AgesNo. of people in millions% that need pacemakersNo of people with pacemakers
Total280 5.6

I live in Needham, Massachusetts. The population of my town is approximately 30,000.  There are fifteen ATMs in town. So I'll assume that each ATM services 2,000 people. I'm going to assume that the population of the U.S. is around 300 million people.  Next I'll divide 2,000 Into 300 million and come up with 150,000 ATMs.

With a "population type" market-sizing case that you think you'll break down by generation, have certain numbers and assumptions planned out in advance. Pick a number like 280 million Americans that is easily divisible by 4 so you'll know in advance how many people per genera¬tion. You wouldn't believe the number of people who stumble through this, come up with odd numbers, and thus start off on the wrong foot.

As in the pacemaker example, I'll assume that there are 280 million Americans and the average life expectancy is 80 years. I'm going to break them down by generation assuming equal numbers within each generation.

Also, when you are determining percentages of the generations, use easy numbers like 1%, 2%, 5%, 10% etc. You want to make it as easy for yourself as you can.

European PC manufacturer

AgesPeople per generaion% that uses printersPeople using printers
Total  180

Your client is a European PC manufacturer and profits have been falling. The client is thinking about entering the printer business and wants to know if it's an attractive business to enter. Estimate the size of the EU printer market.

I'll assume that the population of the European Union is 480 million and the average life expectancy is 80 years. I'm going to break it down by generations. I'm also going to estimate the number of people who use a printer either at or home at work.

We have a 180 million Europeans that use printers. I'll assume that half of them are printer buyers either for their own home or at work. Now we're looking at 90 million people. I further assume that printers are replaced every five years. Thus, 90/5 equals 18 million printers sold each year. If we assume each printer sells for a 100 Euros, that makes a 1.8 billion Euro market.

A second way to do it...

TypeSmall businesses and organizartionsLarge companies and corporations
Number of organizations50.00060
Numbers of printers per organization10100
Total number of printers500.000200.000
Replacement rate1 in 5 years1 in 3 years
Average price per printer500 euro1000 euro
Total market size / revenue potential Iff sold each year times price per printer50 million euroabout 67 million euro

I'm going to divide the buyers up into two groups: commercial buyers and home buyers. Commercial buyers are (i) small organizations and (ii) small and medium-sized enterprises and businesses.

Now for the home market. There are 480 million Europeans. I'll estimate that the average size of the European household is 2.4 people, which means that there are 200 million households. We'll say that a quarter of the households have a printer. That establishes a market of 50 million households. We'll also assume that the life of a printer is 5 years, thus the market for home printers is 10 million printers a year.
So, the home market is 10 million, small business is 100,000, and the corporate market is 66,000 for a grand total of 10,166,000 printers.

There were 165,000 American children born with autism last year. What percentage of the babies born that year are autistic? (Population question)

There are 300 million Americans. I'll assume that the average life expectancy of an American is 80 years  I'll also assume that there even numbers of people in each age category, thus there are the same number of 3 year olds as 73 year olds. 300 million divided by 80 years equal 3.75 million people per age group We can assume that 3.75 million children were born last year; 165,000 divided by 3.75 million equals 0.044 or around 5 percent.

Обязательно ждите продолжения!

Материал подготовила Екатерина Гридина,
На основе Case in Point, Marc P. Cosentino

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