Last visit was: 19 Nov 2025, 18:14 It is currently 19 Nov 2025, 18:14
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
User avatar
carcass
User avatar
Board of Directors
Joined: 01 Sep 2010
Last visit: 17 Nov 2025
Posts: 4,754
Own Kudos:
37,015
 [12]
Given Kudos: 4,856
Posts: 4,754
Kudos: 37,015
 [12]
6
Kudos
Add Kudos
6
Bookmarks
Bookmark this Post
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Nov 2025
Posts: 105,390
Own Kudos:
778,372
 [1]
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,390
Kudos: 778,372
 [1]
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Kritesh
Joined: 13 Oct 2016
Last visit: 25 Dec 2018
Posts: 183
Own Kudos:
Given Kudos: 418
Concentration: Operations, Leadership
GMAT 1: 600 Q44 V28
GMAT 1: 600 Q44 V28
Posts: 183
Kudos: 813
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 31 Oct 2025
Posts: 6,739
Own Kudos:
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,739
Kudos: 35,355
Kudos
Add Kudos
Bookmarks
Bookmark this Post
carcass
If x books cost $5 each and y books cost $8 each, then the average (arithmetic mean) cost, in dollars per book, is equal to


A) \(\frac{5x+8y}{x+y}\)

B) \(\frac{5x+8y}{xy}\)

C) \(\frac{5x+8y}{13}\)

D) \(\frac{40xy}{x+y}\)

E) \(\frac{40xy}{13}\)

Average cost per book = (TOTAL cost of all books)/(total number of books)

GIVEN: x books cost $5 each and y books cost $8 each
Cost of x books at $5 apiece = 5x
Cost of y books at $8 apiece = 8y
TOTAL cost of all books = 5x + 8y

TOTAL number of books = x + y

Average cost per book = (5x + 8y)/(x + y)

Answer: A

Cheers,
Brent
User avatar
ScottTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 14 Oct 2015
Last visit: 19 Nov 2025
Posts: 21,716
Own Kudos:
Given Kudos: 300
Status:Founder & CEO
Affiliations: Target Test Prep
Location: United States (CA)
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 21,716
Kudos: 26,997
Kudos
Add Kudos
Bookmarks
Bookmark this Post
carcass
If x books cost $5 each and y books cost $8 each, then the average (arithmetic mean) cost, in dollars per book, is equal to


A) \(\frac{5x+8y}{x+y}\)

B) \(\frac{5x+8y}{xy}\)

C) \(\frac{5x+8y}{13}\)

D) \(\frac{40xy}{x+y}\)

E) \(\frac{40xy}{13}\)

The average cost of the books is (5x + 8y)/(x + y) dollars.

Answer: A
avatar
RojoC
Joined: 27 Nov 2019
Last visit: 07 Jul 2022
Posts: 8
Given Kudos: 3
Posts: 8
Kudos: 0
Kudos
Add Kudos
Bookmarks
Bookmark this Post
CostX=5
CostY=8
Total Cost = 5x + 8y
Boxes = x+y
Avg Cost = (5x+8y)/(x+y)
User avatar
Nipungupta9081
User avatar
School Moderator - INSEAD Masters
Joined: 07 Jan 2020
Last visit: 10 Aug 2025
Posts: 501
Own Kudos:
Given Kudos: 193
Location: India
GPA: 4
WE:Analyst (Accounting)
Posts: 501
Kudos: 273
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Average cost = Sum of the cost / total number of books

= 5x + 3Y / x + y

= Answer A
User avatar
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,070
Own Kudos:
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,070
Kudos: 19,392
Kudos
Add Kudos
Bookmarks
Bookmark this Post
'x' books cost $5 each: Total cost $5x

'y' books cost $8 each: Total cost $8y

Sum: 5x + 8y

Total: x + y

Average (arithmetic mean): \(\frac{(5x + 8y) }{ (x + y)}\)

Answer A
User avatar
cm291093
Joined: 02 Jul 2019
Last visit: 26 Oct 2025
Posts: 20
Own Kudos:
Given Kudos: 17
Posts: 20
Kudos: 12
Kudos
Add Kudos
Bookmarks
Bookmark this Post
This question is very basic and you need to have the basic understanding for averages.

To find average is this question = {(quantity x) x (price for x) + (quantity y) x (price for y)} / quantiy x + quantity y

which simply translates to (5x+8y)/ x+y
User avatar
PriyanshuR
Joined: 11 Aug 2024
Last visit: 18 Oct 2025
Posts: 42
Own Kudos:
Given Kudos: 46
Location: India
GMAT Focus 1: 595 Q80 V79 DI80 (Online)
GPA: 8.19
GMAT Focus 1: 595 Q80 V79 DI80 (Online)
Posts: 42
Kudos: 3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
total cost = 5x+8y
total number of books = x + y
Average = Total cost/ total number of books = (5x+8y)/x+y
Moderators:
Math Expert
105390 posts
Tuck School Moderator
805 posts