There are x high-level officials (where x is a positive integer). Each

The key is EACH OF which means if there are 2 high level there are 8 mid level and 8*8=64 low level.

So A looks sufficient- BUT, the stem does not say the low level cannot report to more than one mid level managers. Say that 5 low level report to 2 mid level managers, then there can be 1 or 2 high level managers - so not sufficient.

B resolves this- if no one has more than one manager the only solution is to have 1 high level, 1 mid level and 1 low level.

C- combined sufficient.

Posted from GMAT ToolKit

If x = 1, then there's 1 high level, 1 med level, and 1 low level
If x = 2, there's 2 high level, each of whom supervise x^2 = 4, for a total of 8 mid level, each of whom supervise x^3 = 8 for 64 low level.

1 alone: tells you fewer than 60 low level, but x could equal 2 if low level employees report to more than one manager.
2 alone: could be any value for x

1 & 2 combined allow you to definitively answer, so answer is C

Let H,M and L represent High,Medium and Low level officers resp.
By given condition:
if H=1 then M=1 and L=1
if H=2 then M=2*(2^2)=8 and L=8*(2^3)=64

(1) It tells us that L<60, thus only first of the above two situations satisfies. i.e H=1, it won't be true if H>1-->Sufficient
(2) In each of the above two situations, No official is supervised by more than one person as it is given in the question statement itself that each of relatively higher level officers supervise a set of lower level officers--> insufficient

Hence, the correct answer is choice(A)

Hi Bunuel,

I marked A. Could you please explain how does B contribute to the solution.

Thanks in advance.

aimtoteach

I also marked A, not sure how statement 1 contributes to the answer... My reasoning:

Statement 1: tells us that x^3<60

Statement 2: no official is supervised by more than one person: insinuates that x = x^2 = x^3 ... I thought this could only be true for x=1

Please clear up

Reread my reasoning and the question and I retract my statements haha but I am still confused about the questions. I still don't understand how to get the answer though!

But I've realized that statement 1 has more value than I initially thought because it has narrowed the options of x down to 1, 2 or 3...

So what is B giving us that tells us which one it is?

Hello aimtoteach and sabineodf

Let's imagine that we have firm with 10 low level workers and 2 managers.
But we know nothing about hierarchy of this firm. Maybe each manager has 5 dedicated subordinates or maybe it's mix hierarchy and each manager has 10 subordinates: each from this employees has two managers and report to each managers for different tasks.

Second statement clarify situation about hierarchy of firm from the task.

Let's assume that there are 2 high level officials. This means that each of these 2 high level officials supervises 4 (or x^2) mid-level officials, and that each of these 4 mid-level officials supervises 8 (or x^3) low-level officials.

It is possible that the supervisors do not share any subordinates. If this is the case, then, given 2 high level officials, there must be 2(4) = 8 mid-level officials, and 8(8) = 64 low-level officials.

Alternatively, it is possible that the supervisors share all or some subordinates. In other words, given 2 high level officials, it is possible that there are as few as 4 mid-level officials (as each of the 2 high-level officials supervise the same 4 mid-level officials) and as few as 8 low-level officials (as each of the 4 mid-level officials supervise the same 8 low-level officials).

Statement (1) tells us that there are fewer than 60 low-level officials. This alone does not allow us to determine how many high-level officials there are. For example, there might be 2 high level officials, who each supervise the same 4 mid-level officials, who, in turn, each supervise the same 8 low-level officials. Alternatively, there might be 3 high-level officials, who each supervise the same 9 mid-level officials, who, in turn, each supervise the same 27 low-level officials.

Statement (2) tells us that no official is supervised by more than one person, which means that supervisors do not share any subordinates. Alone, this does not tell us anything about the number of high-level officials.

Combining statements 1 and 2, we can test out different possibilities.

If x = 1, there is 1 high-level official, who supervises 1 mid-level official (12 = 1), who, in turn, supervises 1 low-level official (13 = 1).

If x = 2, there are 2 high-level officials, who each supervise a unique group of 4 mid-level officials, yielding 8 mid-level officials in total. Each of these 8 mid-level officials supervise a unique group of 8 low-level officials, yielding 64 low-level officials in total. However, this cannot be the case since we are told that there are fewer than 60 low-level officials.

Therefore, based on both statements taken together, there must be only 1 high-level official. The correct answer is C: BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

(1) There are fewer than 60 low-level officials.
(2) No official is supervised by more than one person.


Stmt 1 gives us two possibilities = x can be 1 or 2. Not sufficient
Stmt 2 doesnt give any conclusive evidence.

Combining both we can conclude x = 1 since if x=2 , 4 unique mid level managers totaling 8 and then 8 unique low level managers totaling 64 people will come which is not possible. So x=1
Option C

This is a tricky question, no where in the question it is mentioned that people reporting to their supervisors are mutually exclusive.
For example, lets say, there are 2 high level officials and there are 4 mid level officials and 8 low level officials. Now without statement 2 we can say that the 4 mid level officials report to both 2 high level officials and same in the case of 8 low level officials (they can report to all the 4 mid level officials.)

Statement 1 - Considering one official is reporting to one supervisor we get x=1; If we consider one official reporting to multiple supervisor, answer may vary.

Statement 2 - This clarifies the above ambiguity.

Hence the answer is C.

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.