GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 14 Oct 2019, 16:27

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58320
If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?  [#permalink]

Show Tags

New post 01 Nov 2018, 00:08
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

56% (01:49) correct 44% (02:05) wrong based on 71 sessions

HideShow timer Statistics

Senior PS Moderator
User avatar
D
Status: It always seems impossible until it's done.
Joined: 16 Sep 2016
Posts: 737
GMAT 1: 740 Q50 V40
GMAT 2: 770 Q51 V42
GMAT ToolKit User Reviews Badge
Re: If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?  [#permalink]

Show Tags

New post 01 Nov 2018, 00:29
Bunuel wrote:
If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?

(1) |m| = 5
(2) m


Hi Bunuel, The statement 2 seems to be incomplete. Please check!

\((n+3)(n-1) - (n-2)(n-1) = m(n-1)\)

On first look, \((n-1)\) seems to be common through out.

\((n-1)[(n+3)-(n-2)] = m(n-1)\)
\((n-1)5 = m(n-1)\)

Hence,

\(n-1 = 0\) OR \(m =5\).

Hence we need one of these two conditions to be true for the equation to hold.

Best Regards,
Gladi
_________________
Regards,
Gladi



“Do. Or do not. There is no try.” - Yoda (The Empire Strikes Back)
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58320
Re: If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?  [#permalink]

Show Tags

New post 01 Nov 2018, 00:32
Gladiator59 wrote:
Bunuel wrote:
If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?

(1) |m| = 5
(2) m


Hi Bunuel, The statement 2 seems to be incomplete. Please check!

\((n+3)(n-1) - (n-2)(n-1) = m(n-1)\)

On first look, \((n-1)\) seems to be common through out.

\((n-1)[(n+3)-(n-2)] = m(n-1)\)
\((n-1)5 = m(n-1)\)

Hence,

\(n-1 = 0\) OR \(m =5\).

Hence we need one of these two conditions to be true for the equation to hold.

Best Regards,
Gladi

________________________
It's m = 5. Edited. Thank you.
_________________
Manager
Manager
User avatar
P
Joined: 09 Jun 2018
Posts: 188
Location: United States
GPA: 3.95
WE: Manufacturing and Production (Energy and Utilities)
GMAT ToolKit User Premium Member
Re: If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?  [#permalink]

Show Tags

New post 01 Nov 2018, 09:50
We can simplify question to:
(n-1)(n+3-n+2) = m(n-1)
(n-1)*5 = m*(n-1)
m*(n-1) - 5*(n-1) = 0
(m-5)*(n-1) = 0 ............. (A)

Now, stmt 1: |m| = 5, i.e. m=5, or m = -5
If m = 5, then (A) becomes 0*(n-1) = 0, so n can be any value.
If m = -5, then (A) becomes -10*(n-1) = 0 or n = 1
Hence insufficient. Eliminate A,D

Now, stmt 2: m = 5, similar to above, (A) becomes 0*(n-1) = 0, so n can be any value.
Hence Insufficient. Eliminate B

Now, Combined, we get the condition, m = 5, again (A) becomes 0*(n-1) = 0, so n can be any value.
Hence insufficient. Eliminate C.

So as per my analysis, answer should be Option E
_________________
If you found this relevant and useful, please Smash that Kudos button!
Intern
Intern
avatar
B
Joined: 06 Oct 2018
Posts: 29
Re: If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?  [#permalink]

Show Tags

New post 03 Nov 2018, 03:07
I am getting answer B. Someone please help :)

(n+3)(n-1) - (n-2)(n-1) = m(n-1)
(n^2+2n-3) - (n^2-3n+2) = m(n-1)
(n^2+2n-3) - n^2+3n-2 =mn-m
5n-5 = mn-m
5(n-1) = m(n-1)
m=5

Stmnt 1) Mod m = 5 --> m=5 or -5
since m=5 m can't be -5, hence insufficient.

Stmnt 2) m=5
sufficient??

Someone please explain. Made a mistake in simplifying question stem?
Senior PS Moderator
User avatar
D
Status: It always seems impossible until it's done.
Joined: 16 Sep 2016
Posts: 737
GMAT 1: 740 Q50 V40
GMAT 2: 770 Q51 V42
GMAT ToolKit User Reviews Badge
Re: If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?  [#permalink]

Show Tags

New post 03 Nov 2018, 03:14
Hi PierTotti17,

You have simplified the stem correctly and arrived at the correct conclusion. For the expression to be true m has to be 5. But the question is asking for the value of n. Once m is 5 we cannot acertain the value of n as it could be anything and still the expression would be true. Plug in values of n=1 and n=10 to see this... Hence we cannot answer the question with st1 and st2 both.

So option (E) is the answer.

Let me know if this makes sense.

Best,
Gladi


PierTotti17 wrote:
I am getting answer B. Someone please help :)

(n+3)(n-1) - (n-2)(n-1) = m(n-1)
(n^2+2n-3) - (n^2-3n+2) = m(n-1)
(n^2+2n-3) - n^2+3n-2 =mn-m
5n-5 = mn-m
5(n-1) = m(n-1)
m=5

Stmnt 1) Mod m = 5 --> m=5 or -5
since m=5 m can't be -5, hence insufficient.

Stmnt 2) m=5
sufficient??

Someone please explain. Made a mistake in simplifying question stem?

_________________
Regards,
Gladi



“Do. Or do not. There is no try.” - Yoda (The Empire Strikes Back)
Intern
Intern
avatar
B
Joined: 06 Oct 2018
Posts: 29
Re: If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?  [#permalink]

Show Tags

New post 03 Nov 2018, 03:38
Gladiator59 wrote:
Hi PierTotti17,

You have simplified the stem correctly and arrived at the correct conclusion. For the expression to be true m has to be 5. But the question is asking for the value of n. Once m is 5 we cannot acertain the value of n as it could be anything and still the expression would be true. Plug in values of n=1 and n=10 to see this... Hence we cannot answer the question with st1 and st2 both.

So option (E) is the answer.

Let me know if this makes sense.

Best,
Gladi


PierTotti17 wrote:
I am getting answer B. Someone please help :)

(n+3)(n-1) - (n-2)(n-1) = m(n-1)
(n^2+2n-3) - (n^2-3n+2) = m(n-1)
(n^2+2n-3) - n^2+3n-2 =mn-m
5n-5 = mn-m
5(n-1) = m(n-1)
m=5

Stmnt 1) Mod m = 5 --> m=5 or -5
since m=5 m can't be -5, hence insufficient.

Stmnt 2) m=5
sufficient??

Someone please explain. Made a mistake in simplifying question stem?



And that's what happens when you skim the question: you look like a muppet. Thanks Gladiator for pointing out where I was going wrong.
:)
GMAT Club Bot
Re: If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?   [#permalink] 03 Nov 2018, 03:38
Display posts from previous: Sort by

If (n + 3)(n − 1) − (n − 2)(n − 1) = m(n − 1), what is the value of n?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne