A department manager distributed a number of pens, pencils, and pads among the staff in the department, with each staff member receiving x pens, y pencils, and z pads. How many staff members were in the department?

(1) The numbers of pens, pencils, and pads that each staff member received were in the ratio 2:3:4, respectively.
(2) The manager distributed a total of 18 pens, 27 pencils, and 36 pads.


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Ok, look the question tells us the following:
Staff Member 1 - x pens, y pencils, z pads
Staff Member 2 - x pens, y pencils, z pads
.
.
.
Staff Member n - x pens, y pencils, z pads
Total no of pens - nx, total no of pencils - ny and total no of pads - nz
Question: What is n?

Stmnt 1: x:y:z = 2:3:4. So values of x, y and z can be 2, 3 and 4 or 4, 6 and 8 or 6, 9 and 12 or any other values in the ratio 2:3:4. They needn't necessarily be 2, 3 and 4. Just the ratio required is 2:3:4.
Of course n can be anything here. Not sufficient.

Stmnt 2: nx = 18, ny = 27 and nz = 36.
Note here that nx:ny:nz = 18:27:36 = 2:3:4 (They had 9 as a common factor)
Since n is a common factor on left side, x:y:z = 2:3:4 (Ratios are best expressed in the lowest form.)

This is a case of what we call "We already knew that." Information given in stmnt 1 is already part of stmnt 2 so it is not possible that stmnt 2 alone is not sufficient but together stmnt 1 and 2 are.

Now to your question:
Why can't we say that the number of staff members must be 9?
Because ratio of 2:3:4 is same as ratio of 6:9:12 which is same as 18:27:36 (When you multiply each number of a ratio by the same number, the ratio remains unchanged).
If 18, 27 and 36 pens, pencils and pads are distributed in the ratio 2:3:4, I could give them all to one person (18:27:36 is the same ratio as 2:3:4), to 3 people (giving them 6 pens, 9 pencils and 12 pads each. 6:9:12 is the same ratio as 2:3:4) or to 9 people (giving them 2 pens, 3 pencils and 4 pads). Hence I don't know how many staff members are there.
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Bump!

Why not B?

If we know that the quantity of goods disbursed was 18/27/36, can we assume that 9 employees received the goods in the ratio 2/3/4?

I got it only by using common sense. Its not tricky if you think about it .
(1) The numbers of pens, pencils, and pads that each staff member received were in the ratio 2:3:4, respectively.
This shows you how many more pads [b]one person[b] gets compared to the number of pencils or pens he gets.

(2)The manager distributed a total of 18 pens, 27 pencils, and 36 pads.
This can give you an idea how many gadgets are there in total to distribute, but we cannot know how many people will take them.

There can be just one person taking all the 18 pens, 27 pencils, 36 pads (in the proportion of 2:3:4 as stated in (1) )
There can be three people, each taking 6 pens, 9 pencils, 12 pads (2:3:4)
There can be 9 people, each taking 2 pens, 3 pencils, 4 pads (2:3:4)

Answer to this question is E:

Start considering (2) ---> if the manager distributes a total of 18 pens, 27 pencils and 36 pads with each person receiving x pens, y pencils and z pads, means that the number of the staff has to be a factor of both 18,27 and 36. That value could be 3 or 9 --> Not sufficient

Now move to (1) ---> Clearly not sufficient as we do not have any information about the total number of persons or pens,pencils and pads distributed. We have just three ratios.

Considering Together ---> We know form (1) that the number of person should be 3 or 9. If people are 3 we have to distribute 18,27 and 36 --> 6pens, 9pencils, 12 pads for each person. If people are 9 we distribute 2 pens, 3 pencils, 4 pads. In both cases the ratio is the same 2:3:4. Hence not Sufficient.

Hope it's clear.

By the way AMAZING FORUM!

When you saw 18, 27 and 36, what came to your mind was that the number of people could have been 9 which would mean that he gave 2 pens, 3 pencils and 4 pads. You know that 9 is divisible by 3. That should make you realize that the number of people could have been 3 too which would mean that the manager distributed 6 pens, 9 pencils and 12 pads. 9 does not have 2 as a factor so it will not work.
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In both options essentially the same information is provided. When you realize that statement 1 is insufficient and that 1 and 2 are effectively same info. immediately mark E.