How much concrete is used on the island of Manhattan?

Case Interview case study hard Market sizing
Recent activity on Apr 03, 2018
3 Answers
2.3 k Views
Anonymous A asked on Apr 02, 2018

I'm interested in seeing a structure to a question that appears impossible/overwhelming , such as

"How much concrete is used on the island of Manhattan?"

How granular of a level is both reasonable for the interviewee and satisfactory as an answer for the interviewer?

(edited)

Overview of answers

Upvotes
  • Upvotes
  • Date ascending
  • Date descending
Best answer
Francesco
Expert
Content Creator
replied on Apr 03, 2018
#1 Coach for Sessions (3.900+) | 1.400+ 5-Star Reviews | Proven Success (➡ InterviewOffers.com | Ex BCG | 9Y+ Coaching

Hi Anonymous,

you can consider the following steps:

  1. Identify where concrete is used; as besides buildings its main use is for bridges and other viability infrastructure, you could probably consider buildings only if the interviewer agrees
  2. Estimate the number of districts of NY with concrete. You should not includes parks and other parts without buildings
  3. Estimate the number of units using concrete per district – eg how many buildings per district
  4. Estimate the amount of concrete per building as percentage of the total volume of the building walls
  5. Multiply 2*3*4 for each segment identified in step 1

Best,

Francesco

Was this answer helpful?
Andrea
Expert
Content Creator
replied on Apr 02, 2018
Former BCG Principal and decision round interviewer

To elaborate on other answer, for each block then you take an assumption of what is empty vs. Concrete volume by multiplying the width and length of block by the avg height of building and then assuming a “density factor” (I.e. how much space in a cubic meter is concrete vs. Empty) and then multiply by the number of blocks with the distinction of high vs low density.

Andrea

Was this answer helpful?
Vlad
Expert
Content Creator
replied on Apr 02, 2018
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School

Hi,

  • You can calculate the number of blocks (Streets an avenues on Manhattan) and the usage of concrete per block.
  • I would split Manhattan blocks into 2 types with heavy (skyscrapers) and non-heavy construction and estimate the usage of concrete in each type of the blocks.
  • Don't forget to subtract Central Park from the total number of blocks

Best

Was this answer helpful?
Francesco gave the best answer

Francesco

Content Creator
#1 Coach for Sessions (3.900+) | 1.400+ 5-Star Reviews | Proven Success (➡ InterviewOffers.com | Ex BCG | 9Y+ Coaching
3,976
Meetings
26,589
Q&A Upvotes
282
Awards
5.0
1453 Reviews