Private Equity puzzles, solved step by step
- Puzzles
- 100
- Traced to a firm
- 22
- Topics
- 12
- Hard
- 30
008A real estate fund is looking at a chain of wedding banquet halls. Roughly how many banquet halls can a city of 50 lakh people support?Real estate PEIndian mid-market PE
Try it first
Which number sets how many halls the city needs?
Show the worked solution
About 360 halls, and the wedding calendar sets that figure, not annual demand. Fifty lakh people marrying once in about 70 years gives roughly 36,000 weddings a year. If half use a hall for 1.5 events each, that is 27,000 hall bookings. Spread evenly that needs only 74 halls, but if 40% fall on 30 peak dates, those dates alone need 360.
How do you get from a population to a number of weddings?
Start with something every listener can check: most people marry once, and a city's population turns over roughly once a lifetime. Take a lifetime of about 70 years. Then 50 lakh people divided by 70 gives about 71,000 people marrying each year, and two people make one wedding, so about 36,000 weddings. A rate built from one human fact, how often a person marries, is easier to defend than a recalled statistic, because the interviewer can follow every step. You can refine it later for a young city or for weddings held in hometowns elsewhere.
Not every wedding uses a banquet hall; some are at home, at temples, on open lawns or in hotels. Assume half use a hall, so 18,000. Many families book a hall for more than one function, a reception or a sangeet as well as the main day, so assume 1.5 hall events each: 27,000 bookings a year. Every one of these is an illustrative assumption to be tested, not a sourced figure.
The same 27,000 hall bookings a year need 74 halls if spread over 365 days, 180 if spread over a 150-day season, and 360 if 40% of them fall on 30 peak dates, so the busiest evenings set the number of halls. Why is 27,000 divided by 365 the wrong answer?
Think of an umbrella shop. Averaged over the year, it sells a few a day, but it must hold stock for the first heavy rain, when everyone wants one at once. A banquet hall cannot store an empty Tuesday and sell it on an auspicious Saturday, so capacity has to match the peak, not the average. Weddings bunch into a season, and within the season onto a small number of favoured dates. If 40% of bookings land on 30 dates, those dates carry about 360 events each, and with one main event a hall per evening, the city needs about 360 halls.
What does this tell an investor about the business?
Utilisation is the economics. A city sized for its peak runs most halls far below capacity most of the year, so a hall's earnings depend on how it fills off-peak dates with corporate events, smaller parties and exhibitions. The ratio here, 360 halls against 74 if demand were even, says average utilisation is around 20% on wedding business alone. Say the weak assumptions out loud: the peak share and the hall share move the answer most, so they are what you would test with local operators.
Where candidates lose it
The common answer divides annual weddings by 365 and lands near 75 halls. It looks tidy and misses the whole point of the question, which is that the wedding calendar is lumpy and halls cannot store capacity.
The other loss is spending three minutes on the wedding count and none on the conclusion. The interviewer wants the investor's reading: peak sets supply, off-peak sets profit.
What the interviewer asks next
- How would you check the 40% peak share without data?
- What revenue would one hall need per booking to earn back a build cost you assume?
- How does the answer change for a city where many weddings happen in hometowns elsewhere?
015An Indian mid-market fund is looking at a regional dairy. Roughly how many litres of milk does a city of 1 crore people consume in a day?Indian mid-market PE
Try it first
Which unit should the estimate be built on?
Show the worked solution
About 25 lakh litres a day. One crore people at four per household is 25 lakh households. A household uses about 0.8 litres a day: 0.25 for tea, 0.35 for drinking and 0.2 for curd and cooking. That is 20 lakh litres at home. Tea stalls, restaurants and sweet shops add perhaps a quarter more, about 5 lakh litres, for roughly 25 lakh in total, or 250 ml a person.
Why build the estimate around a household?
Think about how milk actually enters a home: one or two packets delivered each morning, bought for the whole family. A household is the unit that buys milk and the unit whose uses you can picture, so an assumption made at household level is one the interviewer can check against their own kitchen. One crore people at four per household gives 25 lakh households. The household size is an assumption to state, not a statistic to recite; a city with more single migrants would have smaller households.
Then list the uses. Tea for four people, two cups each, takes about a quarter of a litre. A child's glass or two of drinking milk adds about 0.35. Curd, cooking and the odd sweet take another 0.2. That is 0.8 litres per household per day, and 25 lakh households make 20 lakh litres.
Twenty-five lakh households using about 0.8 litres a day consume 20 lakh litres at home, and out-of-home use at tea stalls, hotels and sweet shops adds about 5 lakh, giving roughly 25 lakh litres a day, or 250 ml a person. What does the household count miss?
Milk drunk outside the home. Tea stalls, restaurants, hotels and sweet shops are large buyers, and leaving them out understates demand in a city where many people take their tea at a stall. Adding a quarter to household use gives 5 lakh litres more and a total of about 25 lakh. Then do the sanity check: 25 lakh litres over 1 crore people is 250 ml a person a day, roughly one glass. If that sounds wrong for the city you have in mind, adjust the assumption you trust least.
How would a fund use this number?
As a frame, not a forecast. For a dairy deal the question is what share of that daily volume the target already sells and what share it could plausibly win, which needs the packaged versus loose milk split more than the total. A dairy selling 2 lakh litres a day here would hold about 8% of the market. Say the weakest assumption out loud, probably the out-of-home share, and say how you would test it: by counting the tea stalls on a few streets.
Where candidates lose it
The common loss is reaching for a remembered national per-person figure and multiplying. Even if the number were right, the interviewer cannot follow it, and a recalled statistic offered as fact is exactly what they are testing you not to do.
The second miss is forgetting out-of-home use. Tea stalls and sweet shops are a large part of urban milk demand, and leaving them out produces a clean, confident and low answer.
What the interviewer asks next
- How would the estimate change for a city with many single migrant workers?
- What share of this volume is likely to be packaged rather than loose, and how would you estimate it?
- How many delivery vehicles would a dairy need to serve 10% of this market?
041Estimate the annual power bill of a data centre with 20 MW of IT capacity, running at 70% utilisation, with a power usage effectiveness (PUE) of 1.4 and a tariff of Rs 7 per kWh.Infrastructure fund
Try it first
Which is closest to the yearly bill?
Show the worked solution
About Rs 120 crore a year. 20 MW at 70% use is 14 MW of IT load. A PUE of 1.4 means the site draws 1.4 times that for cooling and losses, 19.6 MW. Running all year, 19.6 MW times 8,760 hours is about 171.7 million kWh. At Rs 7 a kWh that is about Rs 1,202 million, or Rs 120 crore. The tariff is an assumption to check.
What does PUE add to the bill?
A home air conditioner does not just cool the room; it also uses power to run its own compressor and fan. Power usage effectivenessTotal power drawn by the whole facility divided by the power used by the IT equipment alone. 1.0 would mean no overhead at all. is total site power divided by IT power, so a PUE of 1.4 means every 1 MW of servers needs another 0.4 MW for cooling, power conversion and lighting. Here that is 5.6 MW on top of 14 MW of IT load, and the bill pays for all 19.6.
20 MW of IT capacity at 70% use draws 19.6 MW once a PUE of 1.4 adds cooling and losses, which over 8,760 hours is 171.7 million kWh and about Rs 120 crore a year at an assumed Rs 7 per kWh. How do you keep the units straight out loud?
Convert once, early, and say it. One megawatt running for one hour is 1,000 kWh, so 19.6 MW for a year is 19.6 x 8,760 x 1,000, about 171.7 million kWh. Then price it: Rs 7 times 171.7 million is about Rs 1,202 million. A crore is ten million, so divide by ten: Rs 120 crore. Most wrong answers to this question are right in method and a factor of ten off in units.
The relationshipC IT capacity, 20 MW u utilisation, 70% PUE total power over IT power, 1.4 p tariff, Rs 7 per kWh, an assumption What it says in wordsMultiply the power actually drawn by the hours in a year, convert to kWh, and price it.Now the investor's view. Power is usually the largest running cost of a data centre, so PUE is an economic number, not a technical one: improving it from 1.4 to 1.3 saves about Rs 8.6 crore a year here. Many colocation contracts pass power through to tenants, which shifts who bears the tariff risk. Ask how the contracts treat power before you treat the bill as the owner's cost.
Where candidates lose it
The common loss is a factor of ten in the units: candidates convert MW to kWh correctly and then slip between million and crore, landing at Rs 12 crore or Rs 1,200 crore. Say each conversion out loud.
The second loss is pricing only the IT load and forgetting the PUE, which understates the bill by 40% and misses the point of the question.
What the interviewer asks next
- What tariff would make the bill Rs 150 crore?
- If utilisation rises to 90%, what happens to the bill and to the PUE?
- In a colocation contract, who usually pays for power, and why does that matter to the investor?
065Size the annual revenue pool of private dental clinics in an Indian metro of 1.2 crore people. Then say what share of it a rollup of 60 clinics could hold.Indian mid-market PEMid-market buyout fund
Try it first
On these assumptions, roughly what share of private visits could 60 clinics handle?
Show the worked solution
About Rs 720 crore a year, of which 60 clinics could hold roughly 7.5%. Take 25% of 1.2 crore people seeing a dentist, 2 visits each and 80% of visits at private clinics: 48 lakh visits. At Rs 1,500 a visit that is Rs 720 crore. Sixty clinics at 20 visits a day for 300 days handle 3.6 lakh visits, about Rs 54 crore of revenue. Every input is an assumption to be tested.
Why build the market from visits rather than from spend per person?
Think of sizing the market for haircuts. Average spend per person hides the fact that some people go monthly and others never; counting the people who go, how often, and what one cut costs is easier to defend line by line. A visit-based tree gives you inputs you can each test separately, and it produces the same unit, visits, that a clinic's capacity is measured in. That second point is why it suits a rollup question: the market and the business are counted in the same currency.
A metro of 1.2 crore people produces about 48 lakh private dental visits a year on these assumptions, worth about Rs 720 crore at Rs 1,500 a visit, and 60 clinics doing 6,000 visits each would handle 7.5% of them, about Rs 54 crore of revenue. How do you test the demand side against supply?
Turn the visits into clinics and see if the number feels right. Forty eight lakh visits over 300 working days is 16,000 visits a day; at 15 a day for a small single-dentist clinic, that is about 1,067 clinic-equivalents. If a local count found far more or far fewer clinics than that, one of the demand assumptions is wrong, most likely the share who visit or the fee. Say that you would check it with a street count in two or three neighbourhoods before trusting the total.
Input Assumption Result Population 1.2 crore Share who visit a dentist in a year 25% 30 lakh patients Visits per patient 2 60 lakh visits Share at private clinics 80% 48 lakh visits Average revenue per visit Rs 1,500 Rs 720 crore 60-clinic rollup capacity 6,000 visits each 7.5% share Each line is an assumption to be tested; together they give about Rs 720 crore of private clinic revenue and a 7.5% capacity share for a 60-clinic rollup. What does the share tell a buyout investor?
It frames the thesis. At about 7.5%, the rollup would be the largest single brand in a fragmented market without needing to win most patients, which is the shape a rollup thesis wants. The limits matter as much: the fee per visit blends cheap check-ups with expensive implants, so a chain that skews to higher-value treatment could earn more from the same visits, and capacity is not demand. Sixty clinics only reach 3.6 lakh visits if patients actually come.
Where candidates lose it
Candidates often multiply the whole population by an annual spend and get a number they cannot defend, or forget that many visits happen at government hospitals and charitable clinics, which a private chain cannot capture.
The second miss is stopping at the market size. The question asks for the rollup's share, which needs one clinic's capacity stated in the same unit as the market.
What the interviewer asks next
- Implants are 10% of visits but half of revenue. How does that change the sizing?
- How would you test the 25% visit rate without any published data?
- What would make you worry that 60 clinics cannot fill their chairs?
