 It is currently 17 Jun 2019, 23:56 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

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. A tailor used 30 buttons that had an average (arithmetic mea  Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Founder  Joined: 18 Apr 2015
Posts: 6885
Followers: 114

Kudos [?]: 1339 , given: 6306

A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
Expert's post 00:00

Question Stats: 78% (01:15) correct 21% (01:20) wrong based on 70 sessions

A tailor used 30 buttons that had an average (arithmetic mean) weight of x grams per button and 20 other buttons that had an average weight of 80 grams per button. Which of the following is the average weight per button, in grams, of the 50 buttons that the tailor used?

A) $$\frac{x + (20)(80)}{50}$$

B) $$\frac{x + 80}{50}$$

C) $$\frac{3}{5} x + \frac{8}{5}$$

D) $$\frac{3}{5}x + 32$$

E) $$\frac{3}{5} x$$
[Reveal] Spoiler: OA

_________________ GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4810
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 117

Kudos [?]: 1895  , given: 397

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
1
KUDOS
Expert's post
Explanation

Total number of buttons used = 50 (30 +20).

Number of buttons that weighs x grams per button = 30

The total mass of buttons that weighs x grams per button = 30x.

Number of buttons that weighs x grams per button = 20

Total mass of buttons that weighs 80 grams per button = $$80 \times 20$$ = 1600.

Total mass of 50 buttons = 30x + 160.

Average mass of buttons = $$\frac{30x + 160}{50}= \frac{3}{5}x + 32$$.

Hence option D is correct.
_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test Intern Joined: 17 Aug 2017
Posts: 4
Followers: 0

Kudos [?]: 7  , given: 0

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
6
KUDOS
@Sandy, really weird answer: B/C 80 x 20 would be 1600 not 160. But in my version of the question, the answer was 3/5x + 32. Hence 80x20 = 1600. Hence (30x + 1600) / 50. Which would equal out to 3/5x + 32. Intern Joined: 08 Apr 2018
Posts: 44
Followers: 0

Kudos [?]: 15  , given: 16

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
2
KUDOS
Carcass wrote:

A tailor used 30 buttons that had an average (arithmetic mean) weight of x grams per button and 20 other buttons that had an average weight of 80 grams per button. Which of the following is the average weight per button, in grams, of the 50 buttons that the tailor used?

A) $$\frac{x + (20)(80)}{50}$$

B) $$\frac{x + 80}{50}$$

C) $$\frac{3}{5} x + \frac{8}{5}$$

D) $$\frac{3}{5}x + 3.2$$

E) $$\frac{5}{8} x$$

Hi Sandy, Please check this answer or your question. 80 x 20 = 1600 not 160 (80 x 2). The answer should be 3/5(x) + 32. Director Joined: 09 Nov 2018
Posts: 508
Followers: 0

Kudos [?]: 27  , given: 1

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
1
KUDOS
sandy wrote:
Explanation

Total mass of buttons that weighs 80 grams per button = $$80 \times 20$$ = 160.

Total mass of 50 buttons = 30x + 160.

Average mass of buttons = $$\frac{30x + 160}{50}= \frac{3}{5}x + 3.2$$.

Hence option D is correct.

Sandy, please fix the error 80*20 = 1600 not 160
so that instead of the part 3.2, becomes 32.
Supreme Moderator
Joined: 01 Nov 2017
Posts: 370
Followers: 5

Kudos [?]: 111 , given: 4

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
Expert's post
Carcass wrote:

A tailor used 30 buttons that had an average (arithmetic mean) weight of x grams per button and 20 other buttons that had an average weight of 80 grams per button. Which of the following is the average weight per button, in grams, of the 50 buttons that the tailor used?

A) $$\frac{x + (20)(80)}{50}$$

B) $$\frac{x + 80}{50}$$

C) $$\frac{3}{5} x + \frac{8}{5}$$

D) $$\frac{3}{5}x + 32$$

E) $$\frac{5}{8} x$$

Another way is to take a value for x..
let x be 80, so the overall average will remain 80.
let us see which value gives us 80 as an answer..

A) $$\frac{x + (20)(80)}{50}...... => \frac{80 + (20)(80)}{50}=\frac{8+160}{5}$$...NO

B) $$\frac{x + 80}{50}.........=>160/50$$....NO

C) $$\frac{3}{5} x + \frac{8}{5}......=>\frac{3}{5} 80 + \frac{8}{5}=8(30+1)/5$$....NO

D) $$\frac{3}{5}x + 32........=>\frac{3}{5}80 + 32=3*16+32=48+32=80$$....YES

E) $$\frac{5}{8} x......=>80*5?8=50$$...NO

D
_________________

Some useful Theory.
1. Arithmetic and Geometric progressions : https://greprepclub.com/forum/progressions-arithmetic-geometric-and-harmonic-11574.html#p27048
2. Effect of Arithmetic Operations on fraction : https://greprepclub.com/forum/effects-of-arithmetic-operations-on-fractions-11573.html?sid=d570445335a783891cd4d48a17db9825
3. Remainders : https://greprepclub.com/forum/remainders-what-you-should-know-11524.html
4. Number properties : https://greprepclub.com/forum/number-property-all-you-require-11518.html
5. Absolute Modulus and Inequalities : https://greprepclub.com/forum/absolute-modulus-a-better-understanding-11281.html

Founder  Joined: 18 Apr 2015
Posts: 6885
Followers: 114

Kudos [?]: 1339 , given: 6306

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
Expert's post
Fixed above the explanation provided by sandy.

Thank you so much guys.

Regards
_________________
Director Joined: 09 Nov 2018
Posts: 508
Followers: 0

Kudos [?]: 27 , given: 1

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
Carcass wrote:
Fixed above the explanation provided by sandy.

Thank you so much guys.

Regards

I think still typo in calculation part it is 1600 not 160
Director Joined: 09 Nov 2018
Posts: 508
Followers: 0

Kudos [?]: 27 , given: 1

Re: A tailor used 30 buttons that had an average (arithmetic mea [#permalink]
AE wrote:
Carcass wrote:
Fixed above the explanation provided by sandy.

Thank you so much guys.

Regards

sandy wrote:

Total mass of buttons that weighs 80 grams per button = $$80 \times 20$$ = 1600.

Total mass of 50 buttons = 30x + 160.

Average mass of buttons = [m]\frac{30x + 160}{50}

I think still typo in calculation part it is 1600 not 160 Re: A tailor used 30 buttons that had an average (arithmetic mea   [#permalink] 10 Jan 2019, 14:05
Display posts from previous: Sort by

A tailor used 30 buttons that had an average (arithmetic mea  Question banks Downloads My Bookmarks Reviews Important topics  Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.