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# If x is a positive integer less than 10, is z greater than

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Senior Manager
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If x is a positive integer less than 10, is z greater than  [#permalink]

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24 Feb 2012, 16:50
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65% (hard)

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57% (02:08) correct 43% (02:38) wrong based on 320 sessions

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If x is a positive integer less than 10, is z greater than the average (arithmetic mean) of x and 10 ?

(1) The positive difference between z and x is greater than the positive difference between z and 10.
(2) z = 5x

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Re: If x is a positive integer less than 10, is z greater than  [#permalink]

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24 Feb 2012, 22:15
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If x is a positive number less than 10, is z greater than the average (arithmetic mean) of x and 10?

Given: $$0<x<10$$. Question: is z greater than the average of x and 10? Or: is $$z>\frac{10+x}{2}$$? --> $$2z>10+x$$?

(1) The positive difference between z and x is greater than the positive difference between z and 10 --> $$|z-x|>|z-10|$$, which means that the distance between z and x is greater than the distance between z and 10:

x-----average-----10-----
(average of x and 10 halfway between x and 10).

Now, as the distance between z and x is greater than the distance between z and 10, then z is either in the blue area, so more than average OR in the green area, so also more than average. Answer to the question YES.

Sufficient.

(2) z = 5x --> is $$2z>10+x$$? --> is $$10x>10+x$$? --> is $$x>\frac{10}{9}$$. We don't now that. Not sufficient. (we've gotten that if $$x>\frac{10}{9}$$, then the answer to the question is YES, but if $$0<x\leq{\frac{10}{9}}$$, then the answer to the question is NO.)

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https://gmatclub.com/forum/if-y-is-a-ne ... 95138.html
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https://gmatclub.com/forum/if-x-and-z-a ... 55651.html

Hope it helps.
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Re: If x is a positive integer less than 10, is z greater than  [#permalink]

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25 Feb 2012, 03:07
1
Thanks Bunuel - I am struggling to understand this:

Now, as the distance between z and x is greater than the distance between z and 10, then z is either in the blue area, so more than average OR in the green area, so also more than average.
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Re: If x is a positive integer less than 10, is z greater than  [#permalink]

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25 Feb 2012, 03:17
enigma123 wrote:
Thanks Bunuel - I am struggling to understand this:

Now, as the distance between z and x is greater than the distance between z and 10, then z is either in the blue area, so more than average OR in the green area, so also more than average.

x-----average-----10-----

Just try to place z in the green or blue area and you'll see that the distance between z and x will be greater than the distance between z and 10;

Now, place z in the red area (or to the left of x) and you'll see that the distance between z and x will be less than the distance between z and 10.

So we have that in order the distance between z and x to be greater than the distance between z and 10 it must be either in blue or red areas so in any case z is more than the average.

Hope it's clear.
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Re: If x is a positive integer less than 10, is z greater than  [#permalink]

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27 Feb 2012, 22:12
Hi,
while solving statement A, I took the following critical points to solve the eqn |z-x|>|z-10|
x<z<10 : True .. Also the answer
z>10: solving this I got x<10. which is information given in the question stem. I dint know how this can answer the ques. hence, considered A as insufficient .. Pl help

Bunuel wrote:
If x is a positive number less than 10, is z greater than the average (arithmetic mean) of x and 10?

Given: $$0<x<10$$. Question: is z greater than the average of x and 10? Or: is $$z>\frac{10+x}{2}$$? --> $$2z>10+x$$?

(1) The positive difference between z and x is greater than the positive difference between z and 10 --> $$|z-x|>|z-10|$$, which means that the distance between z and x is greater than the distance between z and 10:

x-----average-----10-----
(average of x and 10 halfway between x and 10).

Now, as the distance between z and x is greater than the distance between z and 10, then z is either in the blue area, so more than average OR in the green area, so also more than average. Answer to the question YES.

Sufficient.

(2) z = 5x --> is $$2z>10+x$$? --> is $$10x>10+x$$? --> is $$x>\frac{10}{9}$$. We don't now that. Not sufficient. (we've gotten that if $$x>\frac{10}{9}$$, then the answer to the question is YES, but if $$0<x\leq{\frac{10}{9}}$$, then the answer to the question is NO.)

Similar question: 600-level-question-95138.html

Hope it helps.
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Posts: 55188
Re: If x is a positive integer less than 10, is z greater than  [#permalink]

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27 Feb 2012, 23:07
devinawilliam83 wrote:
Hi,
while solving statement A, I took the following critical points to solve the eqn |z-x|>|z-10|
x<z<10 : True .. Also the answer
z>10: solving this I got x<10. which is information given in the question stem. I dint know how this can answer the ques. hence, considered A as insufficient .. Pl help

Bunuel wrote:
enigma123 wrote:
If x is a positive integer less than 10, is z less than the average (arithmetic mean) of x and 10 ?

(1) The positive difference between z and x is greater than the positive difference between z and 10.
(2) z = 5x

Any idea guys how come the answer is A?

If x is a positive number less than 10, is z greater than the average (arithmetic mean) of x and 10?

Given: $$0<x<10$$. Question: is z greater than the average of x and 10? Or: is $$z>\frac{10+x}{2}$$? --> $$2z>10+x$$?

(1) The positive difference between z and x is greater than the positive difference between z and 10 --> $$|z-x|>|z-10|$$, which means that the distance between z and x is greater than the distance between z and 10:

x-----average-----10-----
(average of x and 10 halfway between x and 10).

Now, as the distance between z and x is greater than the distance between z and 10, then z is either in the blue area, so more than average OR in the green area, so also more than average. Answer to the question YES.

Sufficient.

(2) z = 5x --> is $$2z>10+x$$? --> is $$10x>10+x$$? --> is $$x>\frac{10}{9}$$. We don't now that. Not sufficient. (we've gotten that if $$x>\frac{10}{9}$$, then the answer to the question is YES, but if $$0<x\leq{\frac{10}{9}}$$, then the answer to the question is NO.)

Similar question: 600-level-question-95138.html

Hope it helps.

You don't need to work with absolute values here. Again, in order the distance between z and x to be greater than the distance between z and 10 (in order first statement tot hold true) z MUST be to the right of the average, so more than it.
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Re: If x is a positive integer less than 10, is z greater than  [#permalink]

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21 Jun 2015, 01:49
Bunuel wrote:
If x is a positive number less than 10, is z greater than the average (arithmetic mean) of x and 10?

Given: $$0<x<10$$. Question: is z greater than the average of x and 10? Or: is $$z>\frac{10+x}{2}$$? --> $$2z>10+x$$?

(1) The positive difference between z and x is greater than the positive difference between z and 10 --> $$|z-x|>|z-10|$$, which means that the distance between z and x is greater than the distance between z and 10:

x-----average-----10-----
(average of x and 10 halfway between x and 10).

Now, as the distance between z and x is greater than the distance between z and 10, then z is either in the blue area, so more than average OR in the green area, so also more than average. Answer to the question YES.

Sufficient.

(2) z = 5x --> is $$2z>10+x$$? --> is $$10x>10+x$$? --> is $$x>\frac{10}{9}$$. We don't now that. Not sufficient. (we've gotten that if $$x>\frac{10}{9}$$, then the answer to the question is YES, but if $$0<x\leq{\frac{10}{9}}$$, then the answer to the question is NO.)

Similar question: 600-level-question-95138.html

Hope it helps.

If the question said Z is less than the average of X & 10, would be get a yes answer only from the second statement as X<10/9 which would be 1 and avg would be 5.5. Z would be 5 and less than average?
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Re: If x is a positive integer less than 10, is z greater than  [#permalink]

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07 Apr 2019, 05:28
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Re: If x is a positive integer less than 10, is z greater than   [#permalink] 07 Apr 2019, 05:28
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# If x is a positive integer less than 10, is z greater than

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