• 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

There are 7 players in a bowling team with an average...

This topic has 5 expert replies and 0 member replies

There are 7 players in a bowling team with an average...

Post
There are 7 players in a bowling team with an average weight of 85kg. If two new players join the team, one weight 110 kg and the second weight 60 kg, what will be the new average weight?

A. 75 kg
B. 80 kg
C. 85 kg
D. 90 kg
E. 92 kg

The OA is C.

Please, can any expert explain this PS question for me? I tried to solve it of the following way but I'm not sure,

Can I say that,
$$N_{avg}=\frac{85+\left(\frac{110+60}{2}\right)}{2}=85\ kg$$
I need your help. Thanks.

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Top Reply
Post
EconomistGMATTutor wrote:
Hi swerve,
Let's take a look at your question.

We have three numbers, one is 85, average of 7 numbers and other two are 110 and 60.
We can find average of these three numbers as:
$$Average\ =\ \frac{85+110+60}{3}=\frac{255}{3}=85$$
Therefore, option B is correct.

Hope it helps.
I am available if you's like any follow up.
EconomistGMAT - You got the right answer, but your math was faulty here. It is only because the two additional numbers average to 85 that this works out.

Imagine instead that the two new weights were 105 and 110. We could not simply take (85 + 105 + 110)/3 and get 100.

There were 7 players with a weight of 85, so there would be 9 players in total: (7(85) + 100 + 110)/9 = 90. This is weighted toward the 7 players with a lower average weight.

On this actual problem, Mitch and Rich rightly pointed out that because the 2 new weights average to the old average of 85, we don't have to do any additional math. If we didn't notice this, though, and wanted to do the math, the correct formula would be:
$$Average\ =\ \frac{7*85+110+60}{9}=85$$

_________________


Ceilidh Erickson
Manhattan Prep GMAT & GRE instructor
EdM in Mind, Brain, and Education
Harvard Graduate School of Education


Manhattan Prep instructors all have 99th+ percentile scores and expert teaching experience.
Sign up for a FREE TRIAL, and learn why we have the highest ratings in the GMAT industry!

  • +1 Upvote Post
  • Quote
  • Flag
Free Manhattan Prep online events - The first class of every online Manhattan Prep course is free. Classes start every week.

GMAT/MBA Expert

Elite Legendary Member
Joined
23 Jun 2013
Posted:
10197 messages
Followed by:
497 members
Upvotes:
2867
GMAT Score:
800
Top Reply
Post
Hi swerve,

We're told that 7 players on a bowling team have an average weight of 85kg and that two new players join the team (one weighing 110 kg and the other weighing 60 kg). We're asked for the average weight of the 'new' team.

This question be solved in a couple of different ways. Here's how you can solve it without doing too much math - focusing instead on the 'net effect' that the two 'new' weights would have on the average...

110kg is 25kg "more" than the current average (re: 85kg).
60kg is 25kg "less" than the current average (re: 85kg).

Thus, the 'increase' from the heavier person is 'cancelled out' by the 'decrease' from the lighter person... and the average weight of the group would stay the SAME.

Final Answer: C

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

_________________
Contact Rich at Rich.C@empowergmat.com

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post
Quote:
There are 7 players in a bowling team with an average weight of 85kg. If two new players join the team, one weight 110 kg and the second weight 60 kg, what will be the new average weight?

A. 75 kg
B. 80 kg
C. 85 kg
D. 90 kg
E. 92 kg

The OA is C.

Please, can any expert explain this PS question for me? I tried to solve it of the following way but I'm not sure,
Hi swerve,
Let's take a look at your question.

We have three numbers, one is 85, average of 7 numbers and other two are 110 and 60.
We can find average of these three numbers as:
$$Average\ =\ \frac{85+110+60}{3}=\frac{255}{3}=85$$
Therefore, option B is correct.

Hope it helps.
I am available if you's like any follow up.

_________________
GMAT Prep From The Economist
We offer 70+ point score improvement money back guarantee.
Our average student improves 98 points.

  • +1 Upvote Post
  • Quote
  • Flag
Free 7-Day Test Prep with Economist GMAT Tutor - Receive free access to the top-rated GMAT prep course including a 1-on-1 strategy session, 2 full-length tests, and 5 ask-a-tutor messages. Get started now.

GMAT/MBA Expert

Post
swerve wrote:
There are 7 players in a bowling team with an average weight of 85kg. If two new players join the team, one weight 110 kg and the second weight 60 kg, what will be the new average weight?

A. 75 kg
B. 80 kg
C. 85 kg
D. 90 kg
E. 92 kg
Average weight of the 7 original players = 85.
Average weight of the 2 new players = (110+60)/2 = 85.
Since the two groups have the same average weight -- 85 -- the MIXTURE of the two groups must also have an average weight of 85.

The correct answer is C.

_________________
Mitch Hunt
Private Tutor for the GMAT and GRE
GMATGuruNY@gmail.com

If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon.

Available for tutoring in NYC and long-distance.
For more information, please email me at GMATGuruNY@gmail.com.
Student Review #1
Student Review #2
Student Review #3

  • +1 Upvote Post
  • Quote
  • Flag
Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now.

GMAT/MBA Expert

Post
swerve wrote:
There are 7 players in a bowling team with an average weight of 85kg. If two new players join the team, one weight 110 kg and the second weight 60 kg, what will be the new average weight?

A. 75 kg
B. 80 kg
C. 85 kg
D. 90 kg
E. 92 kg
The sum of the weights of the 7 bowlers is 7 x 85 = 595. If we add in two new players, the new sum is 595 + 110 + 60 = 765.

So the new average is 765/9 = 85

Alternate Solution:

When looking at the two new weights, we could have noticed that one weight is 25 greater and the other is 25 less than the average, thus creating no change in the average of the weights of the members of the team.

Answer: C

_________________

Jeffrey Miller
Head of GMAT Instruction
jeff@targettestprep.com



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

  • +1 Upvote Post
  • Quote
  • Flag
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist 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
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh

Top First Responders*

1 Ian Stewart 41 first replies
2 Brent@GMATPrepNow 36 first replies
3 Scott@TargetTestPrep 33 first replies
4 Jay@ManhattanReview 30 first replies
5 GMATGuruNY 23 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

159 posts
2 image description Max@Math Revolution

Math Revolution

91 posts
3 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

56 posts
4 image description Ian Stewart

GMATiX Teacher

50 posts
5 image description GMATGuruNY

The Princeton Review Teacher

35 posts
See More Top Beat The GMAT Experts