BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

The average (arithmetic mean) of 9 scores is \(N.\) If a 10th score is then included with the original 9, the average of

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 2276
Joined: Sat Oct 14, 2017 6:10 amFollowed by: 3 members
by VJesus12 » Mon May 11, 2020 6:25 am

Timer

00:00

Answers

A

B

C

D

E

Stats

Difficulty—

The average (arithmetic mean) of 9 scores is \(N.\) If a 10th score is then included with the original 9, the average of the 10 scores is \(T.\) Which of the following expressions represents the value of the 10th score?


(A) \(10(T−N)\)

(B) \(10T−9N\)

(C) \(\dfrac{10T−9N}{10}\)

(D) \(\dfrac{10T−9N}{9}\)

(E) \(\dfrac{10T−9N}{2}\)

[spoiler]OA=B[/spoiler]

Source: GMAT Paper Tests
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

Re: The average (arithmetic mean) of 9 scores is \(N.\) If a 10th score is then included with the original 9, the averag

by Brent@GMATPrepNow » Mon May 11, 2020 9:29 am
VJesus12 wrote: ↑
Mon May 11, 2020 6:25 am
 The average (arithmetic mean) of 9 scores is \(N.\) If a 10th score is then included with the original 9, the average of the 10 scores is \(T.\) Which of the following expressions represents the value of the 10th score?


(A) \(10(T−N)\)

(B) \(10T−9N\)

(C) \(\dfrac{10T−9N}{10}\)

(D) \(\dfrac{10T−9N}{9}\)

(E) \(\dfrac{10T−9N}{2}\)

[spoiler]OA=B[/spoiler]

Source: GMAT Paper Tests
The average (arithmetic mean) of 9 scores is N.
Let A, B, C, D, E, F, G, H, I be the original 9 scores.
So we can write: (A+B+C+D+E+F+G+H+I)/9 = N
Multiply both sides of the equation by 9 to get: A+B+C+D+E+F+G+H+I = 9N


If a 10th score is then included with the original 9, the average of the 10 scores is T
Let J be the 10th score
We can write: (A+B+C+D+E+F+G+H+I+J)/10 = T
Multiply both sides of the equation by 10 to get: A+B+C+D+E+F+G+H+I+J = 10T

Which of the following expressions represents the value of the 10th score?
In other words, which answer choice represents the value of J?

Take: A+B+C+D+E+F+G+H+I+J = 10T
In other words: A+B+C+D+E+F+G+H+I+J = 10T
Substitute to get: 9N+J = 10T
Subtract 9N from both sides of the equation to get: J = 10T - 9N

Answer: B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8155
Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members
Location: Los Angeles, CA
Thanked: 43 times

Re: The average (arithmetic mean) of 9 scores is \(N.\) If a 10th score is then included with the original 9, the averag

by Scott@TargetTestPrep » Wed May 13, 2020 7:58 am
VJesus12 wrote: ↑
Mon May 11, 2020 6:25 am
 The average (arithmetic mean) of 9 scores is \(N.\) If a 10th score is then included with the original 9, the average of the 10 scores is \(T.\) Which of the following expressions represents the value of the 10th score?


(A) \(10(T−N)\)

(B) \(10T−9N\)

(C) \(\dfrac{10T−9N}{10}\)

(D) \(\dfrac{10T−9N}{9}\)

(E) \(\dfrac{10T−9N}{2}\)

[spoiler]OA=B[/spoiler]

Since the sum of the first 9 scores is 9N and the sum of the 10 scores is 10T, then the 10th score must be 10T - 9N.

Answer: B

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1