GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 21 Apr 2019, 01:23

### 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

# A wire that weighs 20 pounds is cut into two pieces so that one of the

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 54376
A wire that weighs 20 pounds is cut into two pieces so that one of the  [#permalink]

### Show Tags

30 Jun 2017, 03:28
00:00

Difficulty:

55% (hard)

Question Stats:

65% (02:06) correct 35% (01:59) wrong based on 63 sessions

### HideShow timer Statistics

A wire that weighs 20 pounds is cut into two pieces so that one of the pieces weighs 16 pounds and is 36 feet long. If the weight of each piece is directly proportional to the square of its length, how many feet long is the other piece of wire?

(A) 9
(B) 12
(C) 18
(D) 24
(E) 27

_________________
Senior Manager
Joined: 28 May 2017
Posts: 283
Concentration: Finance, General Management
Re: A wire that weighs 20 pounds is cut into two pieces so that one of the  [#permalink]

### Show Tags

30 Jun 2017, 03:57
Bunuel wrote:
A wire that weighs 20 pounds is cut into two pieces so that one of the pieces weighs 16 pounds and is 36 feet long. If the weight of each piece is directly proportional to the square of its length, how many feet long is the other piece of wire?

(A) 9
(B) 12
(C) 18
(D) 24
(E) 27

Weight of 2nd piece = 4 pound

Since the weight is directly proportional to the square of its length., we may write
$$\frac{16}{36^2}$$ = $$\frac{4}{x^2}$$

Solving above, we get x = 18

_________________
If you like the post, show appreciation by pressing Kudos button
Director
Joined: 04 Dec 2015
Posts: 750
Location: India
Concentration: Technology, Strategy
WE: Information Technology (Consulting)
Re: A wire that weighs 20 pounds is cut into two pieces so that one of the  [#permalink]

### Show Tags

30 Jun 2017, 04:02
Bunuel wrote:
A wire that weighs 20 pounds is cut into two pieces so that one of the pieces weighs 16 pounds and is 36 feet long. If the weight of each piece is directly proportional to the square of its length, how many feet long is the other piece of wire?

(A) 9
(B) 12
(C) 18
(D) 24
(E) 27

$$20$$ pounds wire is cut into two pieces = $$16$$ pounds $$+$$ $$4$$ pounds

The piece weighs $$16$$ pounds is $$36$$ feet long.

Ratio of weight and length of $$16$$ pounds piece $$= \frac{16}{36^2} = \frac{4 * 4}{36 * 36} = \frac{1}{81}$$

Therefore required ratio of other part would also be $$\frac{1}{81}$$

Ratio $$= \frac{4}{x^2} =$$ $$\frac{1}{81}$$

$$x^2 = 81*4$$ $$=> x = \sqrt{81*4}$$

$$x = 9 * 2 = 18$$

Hence length of $$4$$ pounds wire $$= 18$$

Intern
Joined: 30 May 2013
Posts: 29
GMAT 1: 600 Q50 V21
GMAT 2: 640 Q49 V29
Re: A wire that weighs 20 pounds is cut into two pieces so that one of the  [#permalink]

### Show Tags

30 Jun 2017, 04:07
IMO (c)
Given, weight proportional to square (length)
=> w1 / w2 = square (l1/l2)
=> 16/4 = square (36/l2)
=> l2 = 18

Sent from my GT-N7100 using GMAT Club Forum mobile app
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 5807
Location: United States (CA)
Re: A wire that weighs 20 pounds is cut into two pieces so that one of the  [#permalink]

### Show Tags

04 Jul 2017, 07:52
1
Bunuel wrote:
A wire that weighs 20 pounds is cut into two pieces so that one of the pieces weighs 16 pounds and is 36 feet long. If the weight of each piece is directly proportional to the square of its length, how many feet long is the other piece of wire?

(A) 9
(B) 12
(C) 18
(D) 24
(E) 27

Since the 20-lb wire is cut into two pieces and one of the pieces weighs 16 lbs, the other piece must weigh 4 lbs. Since the 16-lb piece has length of 36 ft and the weight of each piece is directly proportional to the square of its length, we can let x = the length in feet of the 4-lb piece and create the following proportion:

16/36^2 = 4/x^2

16x^2 = 4 * 36^2

4x^2 = 36^2

x^2 = 36^2/2^2

x^2 = 18^2

x = 18

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

Re: A wire that weighs 20 pounds is cut into two pieces so that one of the   [#permalink] 04 Jul 2017, 07:52
Display posts from previous: Sort by

# A wire that weighs 20 pounds is cut into two pieces so that one of the

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.