• EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • 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
  • 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
  • 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
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep

OG 13-PS 16

This topic has 3 expert replies and 2 member replies
didieravoaka Master | Next Rank: 500 Posts Default Avatar
Joined
13 Jan 2015
Posted:
163 messages
Upvotes:
2

OG 13-PS 16

Post Wed Oct 14, 2015 3:58 pm
On Monday, a person mailed 8 packages weighing an average (arithmetic mean) of 1238 pounds, and on Tuesday, 4 packages weighing an average of 1514 pounds. What was the average weight, in pounds, of all the packages the person mailed on both days?

(A) 13 1/3

(B) 13 13/16

(C) 15 1/2

(D) 15 15/16

(E) 16 1/2

OA- A

I understand why the answer is A, but don't understand why in the process 8(12 3/8) becomes 8(99/8) instead of becoming 8(99).

Please explain.

  • +1 Upvote Post
  • Quote
  • Flag
Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
Top Reply
Post Wed Oct 14, 2015 4:44 pm
didieravoaka wrote:
Sorry Brent, I missed the fractions in the question.

Here is the part I don't get...
Weighted average of all packages = (8/12)(12 3/8) + (4/12)(15 1/4)
= (8/12)(99/8) + (4/12)(61/4)

Why we don't have instead,
Weighted average of all packages = (8/12)(12 3/8) + (4/12)(15 1/4)
= (8/12)(99) + (4/12)(61)

Thanks,
Marc
We want to convert MIXED fractions (12 3/8 and 15 1/4) into ENTIRE fractions.
This is the same as rewriting 3 1/2 as 7/2
Notice that 3 1/2 = 3 + 1/2 = 6/2 + 1/2 = 7/2

Likewise, 12 3/9 = 12 + 3/8 = 96/8 + 3/8 = 99/8

Here's a free video on converting fractions: http://www.gmatprepnow.com/module/gmat-arithmetic/video/1065
The part you want starts at 5:40

Cheers,
Brent

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

Check out the online reviews of our course
Come see all of our free resources

  • +1 Upvote Post
  • Quote
  • Flag
Thanked by: didieravoaka
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!
didieravoaka Master | Next Rank: 500 Posts Default Avatar
Joined
13 Jan 2015
Posted:
163 messages
Upvotes:
2
Top Reply
Post Wed Oct 14, 2015 5:00 pm
I got it!

Thanks,

Marc.

  • +1 Upvote Post
  • Quote
  • Flag
Post Wed Oct 14, 2015 4:44 pm
didieravoaka wrote:
Sorry Brent, I missed the fractions in the question.

Here is the part I don't get...
Weighted average of all packages = (8/12)(12 3/8) + (4/12)(15 1/4)
= (8/12)(99/8) + (4/12)(61/4)

Why we don't have instead,
Weighted average of all packages = (8/12)(12 3/8) + (4/12)(15 1/4)
= (8/12)(99) + (4/12)(61)

Thanks,
Marc
We want to convert MIXED fractions (12 3/8 and 15 1/4) into ENTIRE fractions.
This is the same as rewriting 3 1/2 as 7/2
Notice that 3 1/2 = 3 + 1/2 = 6/2 + 1/2 = 7/2

Likewise, 12 3/9 = 12 + 3/8 = 96/8 + 3/8 = 99/8

Here's a free video on converting fractions: http://www.gmatprepnow.com/module/gmat-arithmetic/video/1065
The part you want starts at 5:40

Cheers,
Brent

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

Check out the online reviews of our course
Come see all of our free resources

  • +1 Upvote Post
  • Quote
  • Flag
Thanked by: didieravoaka
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!
didieravoaka Master | Next Rank: 500 Posts Default Avatar
Joined
13 Jan 2015
Posted:
163 messages
Upvotes:
2
Post Wed Oct 14, 2015 5:00 pm
I got it!

Thanks,

Marc.

  • +1 Upvote Post
  • Quote
  • Flag
didieravoaka Master | Next Rank: 500 Posts Default Avatar
Joined
13 Jan 2015
Posted:
163 messages
Upvotes:
2
Post Wed Oct 14, 2015 4:29 pm
Sorry Brent, I missed the fractions in the question.

Here is the part I don't get...
Weighted average of all packages = (8/12)(12 3/8) + (4/12)(15 1/4)
= (8/12)(99/8) + (4/12)(61/4)

Why we don't have instead,
Weighted average of all packages = (8/12)(12 3/8) + (4/12)(15 1/4)
= (8/12)(99) + (4/12)(61)

Thanks,
Marc

  • +1 Upvote Post
  • Quote
  • Flag

Best Conversation Starters

1 lheiannie07 120 topics
2 LUANDATO 62 topics
3 swerve 62 topics
4 ardz24 61 topics
5 AAPL 57 topics
See More Top Beat The GMAT Members...

Most Active Experts

1 image description Scott@TargetTestPrep

Target Test Prep

174 posts
2 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

173 posts
3 image description Rich.C@EMPOWERgma...

EMPOWERgmat

131 posts
4 image description Jeff@TargetTestPrep

Target Test Prep

130 posts
5 image description EconomistGMATTutor

The Economist GMAT Tutor

130 posts
See More Top Beat The GMAT Experts