Table 1 is inconsistent with data?

Question

I understand that we are supposed to ignore table 1 and do the calculation with the simplest method as it is done in the solution.

But the table is inconsistent, it gives a potential revenue of 24,375,000 (off by a factor of 2!).

Calculations:

There are 500k readers reading 12*200=2400 articles per year,

250k reading 12*140=1680 articles per year and another 250k people reading 12*110=1320 articles per year. 5% of articles read are paid for at a price of 0.25. This means people spend (500k*2400+250k*1680+250k*1320)*0.05*0.25=24,375,000 per year.

I think McKinsey wouldn't give data that is inconsistent like that.

Answer 1

Hi Stanislas,

Good catch! I would say one out of every 2 or 3 practice cases has some type of mistake (yup, you heard me right!). In the grand scheme of things, the mistakes are not a big deal and should just glossed over (a good caser will provide the correct number or guide you “around” the mistake).

In a live case there should not be inconsistencies like this.

Answer 2

Yes, you're right. In real cases, usually you don't have those inconsistencies (as the interviewers catch them early on and make sure they are corrected).

Truth is that the majority of practice cases out there are only average. Don't be frustrated if you find other things like this, or if you can't get to the number provided by the case. Sometimes it's the case that is wrong.