Monday Braintease - Two ropes

Good morning monkeys. Its Monday and time to get your brain back into the swing of things. Silver bananas for whoever gets the correct answer first as well as those who explain the thought process to get the right answer well.

You have two ropes, each of which takes 1 hour to burn. But either rope has different densities at different points, so there's no gaurantee of consistency in the time it takes different sections within the rope to burn. How do you use the two ropes to measure 45 minutes?

21 Comments
 
Best Response

Seeing as how both ropes take exactly 1 hour to burn, lighting the rope on both ends would cause the rope to burn completely in 30 minutes. Light the first rope on both ends, while lighting the second rope on one end only. When the rope that was lit on both ends has completely burned out, 30 minutes will have passed and the second rope still has 30 minutes left to burn completely. That rope can be lit on the other end in order to cut that 30 minutes in half and get 15 more minutes total. 30 minutes for the first rope plus 15 more minutes for the second rope = 45 minutes total.

 

Seeing as how both ropes take exactly 1 hour to burn, lighting the rope on both ends would cause the rope to burn completely in 30 minutes. Light the first rope on both ends, while lighting the second rope on one end only. When the rope that was lit on both ends has completely burned out, 30 minutes will have passed and the second rope still has 30 minutes left to burn completely. That rope can be lit on the other end in order to cut that 30 minutes in half and get 15 more minutes total. 30 minutes for the first rope plus 15 more minutes for the second rope = 45 minutes total.

SB For me please

I eat success for breakfast...with skim milk
 

Looks like those two guys had a cheeky little Google.

"After you work on Wall Street it’s a choice, would you rather work at McDonalds or on the sell-side? I would choose McDonalds over the sell-side.” - David Tepper
 

Seeing as how both ropes take exactly 1 hour to burn, lighting the rope on both ends would cause the rope to burn completely in 30 minutes. Light the first rope on both ends, while lighting the second rope on one end only. When the rope that was lit on both ends has completely burned out, 30 minutes will have passed and the second rope still has 30 minutes left to burn completely. That rope can be lit on the other end in order to cut that 30 minutes in half and get 15 more minutes total. 30 minutes for the first rope plus 15 more minutes for the second rope = 45 minutes total.

 
patpatSeeing as how both ropes take exactly 1 hour to burn, lighting the rope on both ends would cause the rope to burn completely in 30 minutes. Light the first rope on both ends, while lighting the second rope on one end only. When the rope that was lit on both ends has completely burned out, 30 minutes will have passed and the second rope still has 30 minutes left to burn completely. That rope can be lit on the other end in order to cut that 30 minutes in half and get 15 more minutes total. 30 minutes for the first rope plus 15 more minutes for the second rope = 45 minutes total.

cheater

I eat success for breakfast...with skim milk
 
melvvvari only need one rope. i shred the rope completely and reconstitute it such that it is of even consistency. burn it til 3/4 is left.

now that is some divergent thinking. SB for moi.

poop from me

I eat success for breakfast...with skim milk
 
TonyPerkis
melvvvari only need one rope. i shred the rope completely and reconstitute it such that it is of even consistency. burn it til 3/4 is left.

now that is some divergent thinking. SB for moi.

poop from me

i use the other rope for autoerotic asphyxiation.

 
Anacott_CEOYou're all right, it wouldn't be hard to cheat, but it's also not hard to remember feedback from previous interviews. Seeing as how I am not a very abstract thinker, I got this question and another question about angle of clock hands wrong previously.

The clock one isn't really abstract thinking though it is. This rope one, I would say, is.

"After you work on Wall Street it’s a choice, would you rather work at McDonalds or on the sell-side? I would choose McDonalds over the sell-side.” - David Tepper
 
Anacott_CEOYou're all right, it wouldn't be hard to cheat, but it's also not hard to remember feedback from previous interviews. Seeing as how I am not a very abstract thinker, I got this question and another question about angle of clock hands wrong previously.

The clock one is good. I first though 0 degrees.

 

Recusandae qui voluptas similique modi. Ipsa dolor cupiditate veniam blanditiis. Et porro ex voluptate. Ut quo non assumenda quia animi quia tempore iusto.

Libero recusandae at similique maiores. Quas est aperiam qui quas suscipit. Quos animi et qui natus sunt illum.

Rem et est vel sint eligendi praesentium. Necessitatibus accusamus eos voluptas voluptatum accusantium. Non similique corrupti reiciendis iure sunt nobis consequatur. In architecto modi perspiciatis. Consequatur in sint tenetur eaque ut molestiae.

Dolores error occaecati accusamus distinctio ab harum. Aut incidunt et sed earum sed ut. Velit eos ipsa commodi vero quaerat expedita earum. Vel eaque in accusantium quaerat et est. Aut in fugiat quis pariatur earum. Ipsa mollitia voluptatibus est aperiam asperiores qui.

Career Advancement Opportunities

June 2026 Investment Banking

  • Evercore 01 99.4%
  • Moelis & Company 01 98.8%
  • JPMorgan 01 98.2%
  • Guggenheim Partners 01 97.7%
  • Morgan Stanley 07 97.1%

Overall Employee Satisfaction

June 2026 Investment Banking

  • Moelis & Company No 99.4%
  • Morgan Stanley 01 98.8%
  • Evercore 01 98.2%
  • BMO Capital Markets 12 97.6%
  • Banco Santander 01 97.1%

Professional Growth Opportunities

June 2026 Investment Banking

  • Moelis & Company No 99.4%
  • Evercore No 98.8%
  • Morgan Stanley 05 98.2%
  • JPMorgan No 97.7%
  • BMO Capital Markets 12 97.1%

Total Avg Compensation

June 2026 Investment Banking

  • Vice President (14) $434
  • Associates (43) $259
  • 3rd+ Year Analyst (8) $210
  • 2nd Year Analyst (22) $179
  • Intern/Summer Associate (13) $156
  • 1st Year Analyst (75) $151
  • Intern/Summer Analyst (65) $101
notes
16 IB Interviews Notes

“... there’s no excuse to not take advantage of the resources out there available to you. Best value for your $ are the...”

Leaderboard

1
redever's picture
redever
99.2
2
Secyh62's picture
Secyh62
99.0
3
BankonBanking's picture
BankonBanking
99.0
4
kanon's picture
kanon
99.0
5
dosk17's picture
dosk17
98.9
6
GameTheory's picture
GameTheory
98.9
7
DrApeman's picture
DrApeman
98.9
8
Betsy Massar's picture
Betsy Massar
98.9
9
CompBanker's picture
CompBanker
98.9
10
Jamoldo's picture
Jamoldo
98.8
success
From 10 rejections to 1 dream investment banking internship

“... I believe it was the single biggest reason why I ended up with an offer...”