Topic “M23 #35” - latest posts

Re: M23 #35

mailpravs — Tue, 07 Sep 2010 02:37:53 -0500

Re: M23 #35

sidhu4u — Sat, 13 Mar 2010 05:05:55 -0600

yup, (x-2) was confusing until I read the question again and figured out that I could use 1.
(x-1) it is.

Re: M23 #35

xyztroy — Fri, 12 Mar 2010 22:54:48 -0600

I also fell for the wording and chose x-2 (A), but now I also agree that the ans should be x-1 or B.

Re: M23 #35

ExecMBA2010 — Fri, 12 Mar 2010 21:25:50 -0600

Plug in 23 for x, f(x) = 22
Plug in another prime 37, f(x) = 36

Ans B

Re: M23 #35

varun2410 — Wed, 10 Mar 2010 21:19:35 -0600

Ans:A

f(2) = 0 = 0 numbers
f(3) = 2 = 1 number
f(5) = 2,3,4 = 3 numbers
f(7) = 2,3,4,5,6 = 5 numbers
f(x) = x-2 numbers
if Ans is b then
f(2) = 1 = 1 numbers
f(3) = 2 = 2 number
f(5) = 4 = 4 numbers
f(7) = 6 = 6 numbers
f(x) = x-1 numbers all numbers other then 1 is having comman factor 2 with x and it is given that x is do not have common factor with f(x)

Re: M23 #35

prabir2001 — Wed, 10 Mar 2010 18:58:18 -0600

Answer should be B.... Need to include '1'.

Re: M23 #35

dmetla — Wed, 10 Mar 2010 13:48:13 -0600

Ans should be x-1

Re: M23 #35

bipolarbear — Wed, 05 Aug 2009 20:39:25 -0500

ah i see it now... this is a tricky gmat problem and even if its part of gmatprep, i think its more of a verbal question than math

Re: M23 #35

viperm5 — Wed, 05 Aug 2009 20:04:53 -0500

bipolarbear wrote:

viperm5 wrote:

bipolarbear wrote:

The answer is wrong. OA should be (A).

f(2) = 0 = 0 numbers
f(3) = 2 = 1 number
f(5) = 2,3,4 = 3 numbers
f(7) = 2,3,4,5,6 = 5 numbers
f(x) = x-2 numbers

bipolar u're forgetting 1.
u need to count 1 as well.
hence f(2) = 1
f(3) = 1,2 -> 2
f(4) = 1,2,3 -> 3

i got this exact question on the gmatprep and answer is x-1.

but the question states f(x) = number of factors OTHER than 1, so you can't count one... but i guess if gmatprep says so

am i just interpreting the question wrong?

i fell for the wording too

f(x) defined as all numbers positive less than x AND do not have same factor with x other than 1....meaning that you DO include x.....

do NOT have ...OTHER THAN 1 - means you include 1.

Re: M23 #35

bipolarbear — Wed, 05 Aug 2009 19:54:47 -0500

viperm5 wrote:

bipolarbear wrote:

The answer is wrong. OA should be (A).

f(2) = 0 = 0 numbers
f(3) = 2 = 1 number
f(5) = 2,3,4 = 3 numbers
f(7) = 2,3,4,5,6 = 5 numbers
f(x) = x-2 numbers

bipolar u're forgetting 1.
u need to count 1 as well.
hence f(2) = 1
f(3) = 1,2 -> 2
f(4) = 1,2,3 -> 3

i got this exact question on the gmatprep and answer is x-1.

but the question states f(x) = number of factors OTHER than 1, so you can't count one... but i guess if gmatprep says so

am i just interpreting the question wrong?

Re: M23 #35

viperm5 — Wed, 05 Aug 2009 19:48:03 -0500

bipolarbear wrote:

The answer is wrong. OA should be (A).

f(2) = 0 = 0 numbers
f(3) = 2 = 1 number
f(5) = 2,3,4 = 3 numbers
f(7) = 2,3,4,5,6 = 5 numbers
f(x) = x-2 numbers

bipolar u're forgetting 1.
u need to count 1 as well.
hence f(2) = 1
f(3) = 1,2 -> 2
f(4) = 1,2,3 -> 3

i got this exact question on the gmatprep and answer is x-1.

Re: M23 #35

bipolarbear — Tue, 04 Aug 2009 21:47:01 -0500

The answer is wrong. OA should be (A).

f(2) = 0 = 0 numbers
f(3) = 2 = 1 number
f(5) = 2,3,4 = 3 numbers
f(7) = 2,3,4,5,6 = 5 numbers
f(x) = x-2 numbers

Re: m23 # 35

sset009 — Fri, 29 Aug 2008 17:48:37 -0500

i was thinking of x = 3

the number of numbers below three that do not have a any factor apart from 1 is 2
since 1 has a factor of 1 itself, it doenst count.
therefore, f(x3) = 1

similarily, f(2) = 0

Re: m23 # 35

x2suresh — Fri, 29 Aug 2008 13:20:29 -0500

stallone wrote:

x-2 for me !

Show me your work.. how did you get x-2

Re: m23 # 35

x2suresh — Fri, 29 Aug 2008 13:19:41 -0500

sset009 wrote:

i disagree with teh OA. just want to get an opinion

I will go with B.
X is prime number..

value 1.2... x-1

there are x-1 integers that are less than x

Re: m23 # 35

stallone — Fri, 29 Aug 2008 13:13:40 -0500

x-2 for me !

Re: m23 # 35

sset009 — Fri, 29 Aug 2008 11:59:54 -0500

i disagree with teh OA. just want to get an opinion

M23 #35

sset009 — Fri, 29 Aug 2008 11:59:22 -0500

If x is a positive integer, f(x) is defined as the number of positive integers which are less than x and do not have common factor with x other than 1. If x is prime then f(x) = ?

(A) x - 2
(B) x - 1
(C) \frac{x + 1}{2}
(D) \frac{x - 1}{2}
(E) 2

[Reveal] Spoiler: OA

Source: GMAT Club Tests - hardest GMAT questions