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 →

For what value of x are the mode, the median and the average

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Moderator
Posts: 2632
Joined: Sun Oct 29, 2017 2:08 pmFollowed by: 2 members
by AAPL » Wed May 30, 2018 5:15 am

Timer

00:00

Answers

A

B

C

D

E

Stats

Difficulty—

P={40, 50, 60, 60, 70, x}

For what value of x are the mode, the median and the average of set P above equal?

A. 20
B. 35
C. 60
D. 80
E. 90

The OA is D.

The mode is absolutely equal to 60. So, the average should be equal to 60.

So, 40+50+60+60+70+x = 6*60 = 360 --> x = 80.

Has anyone another strategic approach to solve this PS question? Regards!
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

by Brent@GMATPrepNow » Wed May 30, 2018 5:26 am
AAPL wrote:P={40, 50, 60, 60, 70, x}

For what value of x are the mode, the median and the average of set P above equal?

A. 20
B. 35
C. 60
D. 80
E. 90

The OA is D.

The mode is absolutely equal to 60. So, the average should be equal to 60.

So, 40+50+60+60+70+x = 6*60 = 360 --> x = 80.

Has anyone another strategic approach to solve this PS question? Regards!
I sincerely doubt that there's a better (i.e., faster) approach than the one you describe.
One option would be to test the answer choices, but your approach is likely faster.

The key concept (which you have identified) is that the mode MUST be 60, since we already have two 60's.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 416
Joined: Thu Oct 15, 2009 11:52 am
Thanked: 27 times

For what value of x are the mode, the median and the average

by regor60 » Wed May 30, 2018 7:22 am
--
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members
Location: Palo Alto, CA
Thanked: 2867 times
GMAT Score:800

by [email protected] » Wed May 30, 2018 3:04 pm
Hi AAPL,

You've correctly deduced that the Mode would have to be 60. You might be able to save on some 'calculation time' if you use the patterns in the numbers to your advantage (meaning that you don't technically have to calculate the entire average by hand to find the value of X).

The numbers are 40, 50, 60, 60, 70 and X.

Notice that 50 is "10 below" the average and 70 is "10 above" the average. Those 'differences' essentially cancel out. 40 is "20 below" the average, so the missing number would have to be '20 above' the average - so that those differences also cancel out...

Final Answer: D

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 1462
Joined: Thu Apr 09, 2015 9:34 amFollowed by: 22 members
Location: New York, NY
Thanked: 39 times

by Jeff@TargetTestPrep » Thu May 31, 2018 3:21 pm
AAPL wrote:P={40, 50, 60, 60, 70, x}

For what value of x are the mode, the median and the average of set P above equal?

A. 20
B. 35
C. 60
D. 80
E. 90
We see that in order for the mode, median and average to be equal, the mode has to be 60. So we can create the equation:

(40 + 50 + 60 + 60 + 70 + x)/6 = 60

280 + x = 360

x = 80

Answer: D

Jeffrey Miller
Head of GMAT Instruction
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1