• NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    Hundreds of Questions Highly Detailed Reporting Expert Explanations TAKE A FREE GMAT QUIZ
  • 7 CATs FREE!
    If you earn 100 Forum Points

    Engage in the Beat The GMAT forums to earn
    100 points for $49 worth of Veritas practice GMATs FREE

    Veritas Prep
    VERITAS PRACTICE GMAT EXAMS
    Earn 10 Points Per Post
    Earn 10 Points Per Thanks
    Earn 10 Points Per Upvote
    REDEEM NOW

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

This topic has 1 expert reply and 1 member reply

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

Post

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Difficult



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.

OA B

Source: GMAT Prep

  • +1 Upvote Post
  • Quote
  • Flag
Top Reply
Post
$10 - first chair
$1 - additional

Order \(n\)

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

(A) delivery cost \(> 30\). Not sufficient.

(B)
\(\begin{align}
S&=An \\
10+(n-1) &= 1.36n \\
9 + n&= 1.36n \\
9 &= 0.36n \\
\frac{9}{0.36} &= n \\
25 &= n
\end{align}\)

Sufficient. Hence, the correct answer is B

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Top Reply
Post
BTGmoderatorDC 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.

OA B

Source: GMAT Prep
Target question: Is n > 24?

Given: The cost of delivery for an order of desk chairs was $10.00 for the 1st chair, and $1 for each additional chair in the order. The office manager placed an order for n desk chairs.

Statement 1: The delivery cost for the order totaled more than $30.00
There are several scenarios that meet this condition. Here are two:
Case a: n = 25, in which case the total cost is $34 (which is more than $30). Here, n is greater than 24.
Case b: n = 23, in which case the total cost is $32 (which is more than $30). Here, n is not greater than 24.
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: The average (arithmetic mean) delivery cost per chair of the n chairs was $1.36
The average cost of n chairs = (total cost of n chairs)/n
The total cost = $10 for the first chair plus $1 for each of the remaining n-1 chairs
Algebraically, we can say that the total cost = 10 + 1(n-1)
So, the average cost of n chairs = [10 + 1(n-1)]/n
Statement 2 says the average cost is $1.36, so we can write:
[10 + 1(n-1)]/n = 1.36
IMPORTANT: We could solve this equation for n (but we won't), which means we could definitively determine whether or not n > 24.
Since we could answer the target question with certainty, statement 2 is SUFFICIENT

Answer = B

Cheers,
Brent

_________________
Brent Hanneson – Creator of GMATPrepNow.com
Use my video course along with Beat The GMAT's free 60-Day Study Guide

Sign up for free Question of the Day emails
And check out all of these free resources

  • +1 Upvote Post
  • Quote
  • Flag
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep

Top First Responders*

1 Ian Stewart 53 first replies
2 Brent@GMATPrepNow 36 first replies
3 Jay@ManhattanReview 29 first replies
4 GMATGuruNY 25 first replies
5 ceilidh.erickson 15 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 image description Scott@TargetTestPrep

Target Test Prep

199 posts
2 image description Max@Math Revolution

Math Revolution

90 posts
3 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

76 posts
4 image description Ian Stewart

GMATiX Teacher

62 posts
5 image description GMATGuruNY

The Princeton Review Teacher

44 posts
See More Top Beat The GMAT Experts