What is the value of \frac{x}{yz} ? (1) x = \frac{y}{2} and

Question

What is the value of  \frac{x}{yz} ?

(1)  x = \frac{y}{2}  and  z = \frac{2x}{5}

(1)  \frac{x}{z}  =  \frac{5}{2}  and  \frac{1}{y}  =  \frac{1}{10}

saurabhkowley18 · Answer

Both statements 1 & 2 by themselves are not sufficient,
but together they are sufficient ......
Hence ans C

Sunny143 · Answer

St1: Gives you x/yz in terms of x...not suff

St2: 
x/yz= 1/4

B

2010mba · Answer

B

x/yz can be made from statement 2 simply by multiplying the values. If you removed the values, you could still get x/z * 1/y = x/zy = x/yz

statement 1 does not give you a value in terms of a variable and is insuff.

greatchap · Answer

Couldnt find this ques in OG11 #90

Moreover Shouldnt the answer be D.

(1) x/yz = ??

x = y/2 and Z = 2x/5

so y/2 / 2x / 5

this means - y/2 * 2*y/2/ 5 ... here cant we replace value of x by y/2
thus we can solve it.

(2) this one can be solved as shown in the post.

pmenon · Answer

B

from stat 1, you would still be left with one variable in the final expression.

from stat 2, you can calculate the value (not that you have to) ... x/y*z is just broken up as (x/z)*(1/y)

greatchap · Answer

Can you tell me what variable will be left in final expression from 1. We can put value of y in x and go ahead. I know from (2) we can solve it.

Oski · Answer

Try to actually solve it from (1) only, you'll see

jallenmorris · Answer

This is not a helpful post. greatchap is asking a question and instead of answering the question, you tell him to "try to solve it from (1) only, you'll see". greatchap obviously has already tried to solve it from (1) and still has questions. Please provide an explanation for the answer or answer the poster's question, otherwise, I don't see the point in posting.

OA is B.

OA is B.

jallenmorris · Answer

greatchap

I first thought it could be solved by #1 also, and it took me some time to figure out that it cannot (certainly longer than 2 min!). 
I took each equation and found in terms of each variable there.

x = \frac{y}{2}  and  y = 2x 
 z = \frac{2x}{5}  and  x = \frac{5z}{2}

Since we know  y = 2x , I also substituted this in for  z = \frac{2x}{5}  so  z = \frac{y}{5}  and  y = 5z .

Now since we know x in terms of z and y in terms of z, I substituted these values in for  x=\frac{y}{2} . This gives us :

\frac{5z}{2} = \frac{5z}{2}  - this doesn't give us any new information about z because no matter what z is, it's identical on the other side. When we have 3 variables, we need 3 different equations to be able to solve with substituting.

Oski · Answer

This was not meant to be rude (hence the smiley).

He says that he can solve it: 
And asks after that why others say that we cannot:

I'm just saying that if he actually continues in the calculation he will see that he cannot get rid of all the variables, that's it.

I think it IS the best way for him to really see that.

For me, using (1) I arrived to  \frac{x}{yz}=\frac{5}{2y}  (and then I cannot do anything about this y)

greatchap · Answer

Solved Thanks a lot guys for your help. I tried solving it again and found out that I was making a mistake earlier. Yes if we continue to solve it we will end up with 5/2y . Earlier I had not written the values properly so I thought it could be solved. Now I got it and know that OA is B. Thanks jallenmorris and oski for helping me out.

What is the value of \frac{x}{yz} ? (1) x = \frac{y}{2} and

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards