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

 It is currently 21 Feb 2019, 02:53

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

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

Events & Promotions

Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar

February 21, 2019

February 21, 2019

10:00 PM PST

11:00 PM PST

Kick off your 2019 GMAT prep with a free 7-day boot camp that includes free online lessons, webinars, and a full GMAT course access. Limited for the first 99 registrants! Feb. 21st until the 27th.
• Free GMAT RC Webinar

February 23, 2019

February 23, 2019

07:00 AM PST

09:00 AM PST

Learn reading strategies that can help even non-voracious reader to master GMAT RC. Saturday, February 23rd at 7 AM PT

The cost of delivery for an order of desk chairs was \$10.00

Author Message
TAGS:

Hide Tags

Intern
Joined: 05 Oct 2011
Posts: 36
The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

06 Dec 2011, 01:20
4
31
00:00

Difficulty:

45% (medium)

Question Stats:

67% (01:57) correct 33% (02:00) wrong based on 1161 sessions

HideShow timer Statistics

The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

(1) The delivery cost for the order totalled more than \$30.00.
(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36.
Math Expert
Joined: 02 Sep 2009
Posts: 53060
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

31 Mar 2012, 16:26
6
8
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

_________________
SVP
Joined: 24 Jul 2011
Posts: 1530
GMAT 1: 780 Q51 V48
GRE 1: Q800 V740

Show Tags

06 Dec 2011, 02:00
4
3
Simple one.

Using (1), the total is to be more than \$30, which can be the case if n is greater than or less than 24. For instance, when n=22, the total cost is \$31, but when n=25, the total cost is \$34, which are both greater than \$30. Insufficient.
Using (2), we are given that [10 + (n-1)]/n = 1.36
=> n= 25, which is greater than 24. Sufficient.

_________________

GyanOne | Top MBA Rankings and MBA Admissions Blog

Premium MBA Essay Review|Best MBA Interview Preparation|Exclusive GMAT coaching

Get a FREE Detailed MBA Profile Evaluation | Call us now +91 98998 31738

General Discussion
Intern
Joined: 22 Mar 2011
Posts: 4

Show Tags

15 Dec 2011, 06:14
1
(1) only tells us n >= 21; not sufficient by itself
(2) tells us [10+n-1]/n = 1.36; which will lead to a definitive answer and therefore is sufficient by itself

Thus, B.
Manager
Joined: 28 Jul 2011
Posts: 178
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

31 Mar 2012, 20:59
2
Vote for B

\$10 - first chair

order n

is n>24? i.e. cost should be least 10(1) + 1(23) = \$33 for 24 chairs

(A) delivery cost > 30

data not sufficient

(B)

S=An
10+(n-1) = 1.36n
9 + n= 1.36n
9 = 0.36n
9/.36 = n
25 = n

Sufficient
Board of Directors
Joined: 01 Sep 2010
Posts: 3353
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

16 Apr 2012, 00:48
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

awesome as you have rephrased the statement,.

We could think also in this way: 1 chair cost 10 and the others 1 more \$. for 24 chairs we have a total of 33 \$. so we could say: is total cost more than 33\$ ??? is correct bunuel ??

also is unclear (n-1) in the formula above is not : Tot= 10 + 1*N ??????? N is the number of chair.....

thanks Moderator.
_________________
Math Expert
Joined: 02 Sep 2009
Posts: 53060
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

16 Apr 2012, 00:58
2
1
carcass wrote:
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

awesome as you have rephrased the statement,.

We could think also in this way: 1 chair cost 10 and the others 1 more \$. for 24 chairs we have a total of 33 \$. so we could say: is total cost more than 33\$ ??? is correct bunuel ??

also is unclear (n-1) in the formula above is not : Tot= 10 + 1*N ??????? N is the number of chair.....

thanks Moderator.

The cost of the first chair is \$10 and \$1 for each additional chair.

So, for n chairs one chair goes for \$10 and the rest n-1 chairs go for \$1 each, total \$10+\$1*(n-1)=9+n.

Hope it's clear.
_________________
Board of Directors
Joined: 01 Sep 2010
Posts: 3353
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

16 Apr 2012, 01:18
I.E. 15 chairs: the first one is 10 \$, 14 chairs are 1 \$ each. our (n-1) is the cost of 1\$ for (15-1).

Totally stupid I'm.

Thanks Bunuel.
_________________
Manager
Joined: 16 Feb 2012
Posts: 174
Concentration: Finance, Economics
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

04 Aug 2013, 06:18
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

I am not so good at translating words to numbers, could you post some similar problems to practice the skill?
_________________

Kudos if you like the post!

Failing to plan is planning to fail.

Verbal Forum Moderator
Joined: 10 Oct 2012
Posts: 611
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

04 Aug 2013, 06:21
1
Stiv wrote:
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

I am not so good at translating words to numbers, could you post some similar problems to practice the skill?

search.php?search_id=tag&tag_id=183 for DS
search.php?search_id=tag&tag_id=56 for PS

Hope this helps.
_________________
Economist GMAT Tutor Instructor
Joined: 01 Oct 2013
Posts: 68
Re: The cost of delivery for an order of desk chairs was \$10,000  [#permalink]

Show Tags

11 Dec 2013, 18:01
Vidhi1 wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n>24?

1. The delivery cost for the order totaled more than \$30.00
2. The average (arithmetic mean) delivery cost of the n chairs was \$1.36

So, now we can see that, for statement 1, the question is how much more than \$30.00? At \$31.00, n<24, while at, say \$300.00, n>24.

For statement 2, from the average and the information in the stem, we can calculate n: (10 + (n-1))/n = 1.36, so n = 25.

So, the correct response is B.
_________________

Economist GMAT Tutor
http://econgm.at/econgmat
(866) 292-0660

Intern
Joined: 27 Apr 2014
Posts: 38
GMAT 1: 710 Q47 V40
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

21 Jul 2014, 03:17
Bunuel wrote:
carcass wrote:
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

awesome as you have rephrased the statement,.

We could think also in this way: 1 chair cost 10 and the others 1 more \$. for 24 chairs we have a total of 33 \$. so we could say: is total cost more than 33\$ ??? is correct bunuel ??

also is unclear (n-1) in the formula above is not : Tot= 10 + 1*N ??????? N is the number of chair.....

thanks Moderator.

The cost of the first chair is \$10 and \$1 for each additional chair.

So, for n chairs one chair goes for \$10 and the rest n-1 chairs go for \$1 each, total \$10+\$1*(n-1)=9+n.

Hope it's clear.

]
worndering where 9+n came from. I was plugging in numbers to find averages - 11, 6, etc...crazy
_________________

Kudos my back and I Kudos your back

Math Expert
Joined: 02 Sep 2009
Posts: 53060
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

21 Jul 2014, 03:23
amenon55 wrote:
Bunuel wrote:
carcass wrote:

awesome as you have rephrased the statement,.

We could think also in this way: 1 chair cost 10 and the others 1 more \$. for 24 chairs we have a total of 33 \$. so we could say: is total cost more than 33\$ ??? is correct bunuel ??

also is unclear (n-1) in the formula above is not : Tot= 10 + 1*N ??????? N is the number of chair.....

thanks Moderator.

The cost of the first chair is \$10 and \$1 for each additional chair.

So, for n chairs one chair goes for \$10 and the rest n-1 chairs go for \$1 each, total \$10+\$1*(n-1)=9+n.

Hope it's clear.

]
worndering where 9+n came from. I was plugging in numbers to find averages - 11, 6, etc...crazy

The cost of the first chair is \$10 and \$1 for each additional chair.

So, for n chairs one chair goes for \$10 and the rest n-1 chairs go for \$1 each, total \$10+\$1*(n-1)=9+n.
_________________
CEO
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2793
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

21 Jul 2015, 05:48
ruturajp wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

(1) The delivery cost for the order totalled more than \$30.00.
(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36.

Given : \$10 for first chair and \$1 for each additional Chair

i.e. Total Cost of n chairs = 10 + (n-1)*1

Question : Is n > 24 ?

Statement 1: The delivery cost for the order totalled more than \$30.00.
10 + (n-1)*1 > 30
i.e. n > 21
NOT SUFFICIENT

Statement 2: The average (arithmetic mean) delivery cost of the n chairs was \$1.36.
[10 + (n-1)*1]/n = 1.36
i.e. 1.36n = 10 + (n-1)
i.e. 0.36n = 9
i.e. n = 25
SUFFICIENT

_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Manager
Joined: 31 Jul 2014
Posts: 128
GMAT 1: 630 Q48 V29
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

07 Sep 2015, 07:16
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

Hi Bunuel
If stmnt 2 would be The average (arithmetic mean) delivery cost of the n chairs was greater than \$1.36
then we get n<25 --> in that case, number of chairs could be 24,23,1, 10 in any case answer will be NO, n>24? NO hence sufficient
am I right?
Math Expert
Joined: 02 Sep 2009
Posts: 53060
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

07 Sep 2015, 07:21
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

Hi Bunuel
If stmnt 2 would be The average (arithmetic mean) delivery cost of the n chairs was greater than \$1.36
then we get n<25 --> in that case, number of chairs could be 24,23,1, 10 in any case answer will be NO, n>24? NO hence sufficient
am I right?

Yes, if it were (9+n)/n>1.36, it still would be sufficient.
_________________
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6978
GMAT 1: 760 Q51 V42
GPA: 3.82
The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

08 Sep 2015, 06:34
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and equations ensures a solution.

The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

(1) The delivery cost for the order totalled more than \$30.00.
(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36.

From the original condition, using cost:c gives us c=10+(n-1)1=9+n and thus we have 2 variable (c,n) and 1 equation (c=9+n). Since we need to match the number of variables and equations, we need 1 more equation and we have 1 each in 1) and 2). Therefore D is likely the answer.

In case of 1), c>30, 9+n>30, n>21 therefore the condition is not sufficient(if the range of que includes the range of con then the condition is sufficient)
In case of 2), c=1.36n=9+n, 1.36n-n=9, 0.36n=9, n=25>24 the answer is yes. The condition is sufficient and therefore the answer is B
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only \$149 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Manager
Joined: 19 Aug 2016
Posts: 84
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

25 Nov 2017, 06:56
GyanOne wrote:
Simple one.

Using (1), the total is to be more than \$30, which can be the case if n is greater than or less than 24. For instance, when n=22, the total cost is \$31, but when n=25, the total cost is \$34, which are both greater than \$30. Insufficient.
Using (2), we are given that [10 + (n-1)]/n = 1.36
=> n= 25, which is greater than 24. Sufficient.

Hi

Is this a+(n-1)d?

where d is 1?
Manager
Joined: 02 Jul 2016
Posts: 108
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

19 Mar 2018, 07:57
Bunuel wrote:
The cost of delivery for an order of desk chairs was \$10.00 for the first chair, and \$1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?

According to the rule given in the stem the cost of delivery for n chairs is \$10+\$1*(n-1)=9+n.

(1) The delivery cost for the order totalled more than \$30.00 --> 9+n>30 --> n>21, so n may or may not be more than 24. not sufficient.

(2) The average (arithmetic mean) delivery cost of the n chairs was \$1.36 --> (average cost)=(total cost)/(# of chairs)=(9+n)/n. We are told that (9+n)/n=1.36 --> we can find the exact numerical value of n. Sufficient.

Hi
Great Explanation Bunuel.
For (2) I tried using the conventional formula for the Sum of n terms of an AP.
i.e. n/2(2*(1st term)+(n-1)*(common difference))
Here the 1st term is 10 and the common difference was 1.

the final equation which I got was

10+((n-1) /2)=1.36

Here I am getting the value of n as negative.
So I chose E.

Please tell me where I am wrong.

EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13569
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: The cost of delivery for an order of desk chairs was \$10.00  [#permalink]

Show Tags

24 Jun 2018, 18:54
Hi All,

We're told that the cost of delivery for an order of desk chairs was \$10.00 for the first chaircand \$1.00 for each additional chair in the order. We're asked if an office manager placed an order for N desk chairs, is N > 24. This is a YES/NO question. This DS question is a nice example of what's called "a question BEHIND the question."; this idea of finding another way to view the question usually occurs a few times on Test Day and makes those particular questions easier to answer.

Since we know what 24 chairs would cost (\$10 for the 1st, \$1 for each additional = \$10 + \$23 = \$33), the question BEHIND the question asks "Did the office manager spend more than \$33?"

1) The delivery cost for the order totalled more than \$30.00.

If it's \$31, then the answer to the question is NO
If it's \$35, then the answer to the question is YES
Fact 1 is INSUFFICIENT.

2) The average delivery cost of the N chairs was \$1.36.

This information is fantastic because we don't actually have to calculate anything. There's only one value of N that will equal \$1.36 exactly. If you change the N, then the average changes. Fact 2 would be enough to tell us exactly what N is, so we'd be able to answer the question (and there would be JUST ONE answer).
Fact 2 is SUFFICIENT.

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save \$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

Re: The cost of delivery for an order of desk chairs was \$10.00   [#permalink] 24 Jun 2018, 18:54
Display posts from previous: Sort by