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

It is currently 08 Dec 2019, 01:35

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

M25-18

  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: 59588
M25-18  [#permalink]

Show Tags

New post 16 Sep 2014, 01:23
3
8
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

55% (01:45) correct 45% (02:03) wrong based on 305 sessions

HideShow timer Statistics

The ratio of the number of employees of three companies X, Y and Z is 3:4:8, respectively. Is the average age of all employees in these companies less than 40 years?


(1) The total age of all the employees in these companies is 600.

(2) The average age employees in X, Y, and Z, is 40, 20, and 50, respectively.

_________________
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59588
Re M25-18  [#permalink]

Show Tags

New post 16 Sep 2014, 01:23
4
1
Official Solution:


Given that the ratio of the number of employees is \(3x:4x:8x\), for some positive multiple \(x\).

The questions asks whether \((average \ age)=\frac{(total \ age)}{(number \ of \ employees)} \lt 40\), or whether \(\frac{(total \ age)}{3x+4x+8x} \lt 40\), which is the same as: is \((total \ age) \lt 600x\)?

(1) The total age of all the employees in these companies is 600. The question becomes: is \(600 \lt 600x\)? Or is \(1 \lt x\). We don't know that: if \(x=1\), then the answer is NO but if \(x \gt 1\), then the answer is YES. Not sufficient.

(2) The average age employees in X, Y, and Z, is 40, 20, and 50, respectively. \((total \ age)=40*3x+20*4x+50*8x=600x\), so the answer to the question is NO. Sufficient.


Answer: B
_________________
Intern
Intern
avatar
B
Joined: 28 Aug 2014
Posts: 8
GMAT 1: 620 Q48 V27
GMAT ToolKit User
Re: M25-18  [#permalink]

Show Tags

New post 20 Oct 2014, 04:20
the second statement in particular;
(2) The average age employees in X, Y, and Z, is 40, 20, and 50, respectively. (total \ age)=40*3x+20*4x+50*8x=600x, so the answer to the question is NO. Sufficient.

we cannot find the answer from this statement, so how come we say its sufficient.

i opted for E because its not possible to get a single solution from both the statements.

how come the answer is B?
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59588
Re: M25-18  [#permalink]

Show Tags

New post 20 Oct 2014, 04:28
sriharsha63 wrote:
the second statement in particular;
(2) The average age employees in X, Y, and Z, is 40, 20, and 50, respectively. (total \ age)=40*3x+20*4x+50*8x=600x, so the answer to the question is NO. Sufficient.

we cannot find the answer from this statement, so how come we say its sufficient.

i opted for E because its not possible to get a single solution from both the statements.

how come the answer is B?


This is an Yes/No DS question. In a Yes/No Data Sufficiency questions, statement(s) is sufficient if the answer is “always yes” or “always no” while a statement(s) is insufficient if the answer is "sometimes yes" and "sometimes no".

The question asks: is the average age of all employees in these companies less than 40 years? As shown in the solution this is the same as asking is \((total \ age) \lt 600x\)? The second statement says that \((total \ age)=600x\), thus the asnwer to the question is NO.

Hope it's clear.
_________________
Intern
Intern
avatar
B
Joined: 28 Aug 2014
Posts: 8
GMAT 1: 620 Q48 V27
GMAT ToolKit User
Re: M25-18  [#permalink]

Show Tags

New post 20 Oct 2014, 05:21
thanks Bunuel, it makes sense now. I wasnt aware about the yes/no DS question!!
Intern
Intern
avatar
Joined: 15 Jul 2014
Posts: 9
Re: M25-18  [#permalink]

Show Tags

New post 22 Oct 2014, 22:11
(1) The total age of all the employees in these companies is 600. The question becomes: is 600 \lt 600x? Or is 1 \lt x. We don't know that: if x=1, then the answer is NO but if x \gt 1, then the answer is YES. Not sufficient.

I dont understand why you ruled out Statement 1. We know that x>1 since there is a given ratio for the employees. isnt that sufficient?
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59588
Re: M25-18  [#permalink]

Show Tags

New post 22 Oct 2014, 23:58
kritiu wrote:
(1) The total age of all the employees in these companies is 600. The question becomes: is 600 \lt 600x? Or is 1 \lt x. We don't know that: if x=1, then the answer is NO but if x \gt 1, then the answer is YES. Not sufficient.

I dont understand why you ruled out Statement 1. We know that x>1 since there is a given ratio for the employees. isnt that sufficient?


We don't know whether x > 1. The ratio could be 3:4:8, which is if x = 1.
_________________
Intern
Intern
avatar
Joined: 10 Mar 2013
Posts: 10
Re: M25-18  [#permalink]

Show Tags

New post 22 Dec 2014, 10:45
1
1
I did this way

B) The ratio of the employees are 3:4:8 and the average age are 40,20 and 50.
If you look, more no. of people are above 40 years old. So obviously average will be greater than 40 so the answer has to be N0.

B is the answer

Bunuel wrote:
kritiu wrote:
(1) The total age of all the employees in these companies is 600. The question becomes: is 600 \lt 600x? Or is 1 \lt x. We don't know that: if x=1, then the answer is NO but if x \gt 1, then the answer is YES. Not sufficient.

I dont understand why you ruled out Statement 1. We know that x>1 since there is a given ratio for the employees. isnt that sufficient?


We don't know whether x > 1. The ratio could be 3:4:8, which is if x = 1.
Intern
Intern
User avatar
B
Joined: 12 Mar 2017
Posts: 5
Location: India
Schools: Ross '20 (S)
GMAT 1: 600 Q43 V30
GPA: 2.8
Re: M25-18  [#permalink]

Show Tags

New post 12 Jul 2017, 03:45
Hi. Why is the first statement insufficient? We basically have been given total age. Dividing that with the sum of ratio given is enough to deduce that the avg age of all employees = 40 yrs.

I answered it as D.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59588
Re: M25-18  [#permalink]

Show Tags

New post 12 Jul 2017, 06:15
maryamtheleadr wrote:
Hi. Why is the first statement insufficient? We basically have been given total age. Dividing that with the sum of ratio given is enough to deduce that the avg age of all employees = 40 yrs.

I answered it as D.


If \(x=1\) (so if the number of employees is 15), then the answer is NO but if \(x \gt 1\) (so if the number of employees is 30, 45, ...), then the answer is YES.
_________________
Senior Manager
Senior Manager
User avatar
G
Joined: 31 May 2017
Posts: 334
GMAT ToolKit User Reviews Badge
Re: M25-18  [#permalink]

Show Tags

New post 13 Mar 2018, 17:57
Interesting question. I answered D assuming the number of employees as 15 i.e x=1 in the first option. Now i get what i missed to consider.

Correct answer is B
Intern
Intern
avatar
B
Joined: 12 Jan 2017
Posts: 34
Location: United States (NY)
Schools: Booth '21 (D)
GMAT 1: 710 Q47 V41
GPA: 3.48
Re: M25-18  [#permalink]

Show Tags

New post 10 Jul 2018, 06:13
Bunuel wrote:
Official Solution:


Given that the ratio of the number of employees is \(3x:4x:8x\), for some positive multiple \(x\).

The questions asks whether \((average \ age)=\frac{(total \ age)}{(number \ of \ employees)} \lt 40\), or whether \(\frac{(total \ age)}{3x+4x+8x} \lt 40\), which is the same as: is \((total \ age) \lt 600x\)?

(1) The total age of all the employees in these companies is 600. The question becomes: is \(600 \lt 600x\)? Or is \(1 \lt x\). We don't know that: if \(x=1\), then the answer is NO but if \(x \gt 1\), then the answer is YES. Not sufficient.

(2) The average age employees in X, Y, and Z, is 40, 20, and 50, respectively. \((total \ age)=40*3x+20*4x+50*8x=600x\), so the answer to the question is NO. Sufficient.


Answer: B


Thanks for explaining this. I solved this correctly but your method is much clearer and takes less time.
I think for anyone else having trouble solving this quickly, one needs to always have a clear and organized workspace. Recognizing the two concepts in play - the unknown ratio multiplier, and how to calculate an average and a total - is crucial, but writing them down and then solving for them is even more important.
Intern
Intern
avatar
B
Joined: 16 Oct 2015
Posts: 3
Re: M25-18  [#permalink]

Show Tags

New post 28 Nov 2019, 09:44
there is no difference between statements 1 and 2..they are saying that the sum of ages is 600....how can B be the answer? what if x > 1...i think answer has to be E
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59588
Re: M25-18  [#permalink]

Show Tags

New post 28 Nov 2019, 23:02
GMAT Club Bot
Re: M25-18   [#permalink] 28 Nov 2019, 23:02
Display posts from previous: Sort by

M25-18

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

Moderators: chetan2u, Bunuel






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