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

 It is currently 19 Feb 2019, 13:09

### 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
Your Progress

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

## Events & Promotions

###### Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
• ### Free GMAT Prep Hour

February 20, 2019

February 20, 2019

08:00 PM EST

09:00 PM EST

Strategies and techniques for approaching featured GMAT topics. Wednesday, February 20th at 8 PM EST
• ### Online GMAT boot camp for FREE

February 21, 2019

February 21, 2019

10:00 PM PST

11:00 PM PST

Kick off your 2019 GMAT prep with a free 7-day boot camp that includes free online lessons, webinars, and a full GMAT course access. Limited for the first 99 registrants! Feb. 21st until the 27th.

# The figure above represents a right circular cylindrical tube made out

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

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 52971
The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

08 Dec 2017, 02:46
1
3
00:00

Difficulty:

75% (hard)

Question Stats:

35% (01:49) correct 65% (02:02) wrong based on 80 sessions

### HideShow timer Statistics

The figure above represents a right circular cylindrical tube made out of paper. The circumference of each circular base is 10 centimeters, the length of AB is 12 centimeters, and BD is a diameter of a base. If the tube is cut along AB, opened and flattened, what is the length of AD in centimeters?

(A) 13
(B) 17
(C) 22
(D) 2√61
(E) √146.5

Attachment:

2017-12-08_1440_002.png [ 6.2 KiB | Viewed 1001 times ]

_________________
Current Student
Joined: 18 Aug 2016
Posts: 623
Concentration: Strategy, Technology
GMAT 1: 630 Q47 V29
GMAT 2: 740 Q51 V38
Re: The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

08 Dec 2017, 03:01
Bunuel wrote:

The figure above represents a right circular cylindrical tube made out of paper. The circumference of each circular base is 10 centimeters, the length of AB is 12 centimeters, and BD is a diameter of a base. If the tube is cut along AB, opened and flattened, what is the length of AD in centimeters?

(A) 13
(B) 17
(C) 22
(D) 2√61
(E) √146.5

Attachment:
2017-12-08_1440_002.png

Radius = >
2*pie * r = 10
r = 5/pie
ABD will be right angle Triangle
AD is Hypotenuse and hence can be calculated
AD = $$\sqrt{(12^2 + (5/pie)^2)}$$
AD = $$\sqrt{(144 + 25/~9.5)} = \sqrt{146.5}$$
E
_________________

We must try to achieve the best within us

Thanks
Luckisnoexcuse

Manager
Joined: 24 Nov 2016
Posts: 151
Re: The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

Updated on: 09 Dec 2017, 08:06
1
Bunuel wrote:

The figure above represents a right circular cylindrical tube made out of paper. The circumference of each circular base is 10 centimeters, the length of AB is 12 centimeters, and BD is a diameter of a base. If the tube is cut along AB, opened and flattened, what is the length of AD in centimeters?

(A) 13
(B) 17
(C) 22
(D) 2√61
(E) √146.5

Attachment:
2017-12-08_1440_002.png

If the tube is opened and flattened, then we have a rectangle with length 12 = AB, and width 10 = the circumference.

Now, lines BD and AC are equal to half the width = 10/2 = 5.

So to find the distance AD, we need to find the diagonal of the rectangle with length 12 = AB and width 5 = BD

$$a^2+b^2=c^2, 12^2+5^2=c^2, 169=c^2, c=13$$

(A) is the answer.

Originally posted by exc4libur on 08 Dec 2017, 05:44.
Last edited by exc4libur on 09 Dec 2017, 08:06, edited 1 time in total.
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8883
Location: Pune, India
Re: The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

08 Dec 2017, 06:15
2
1
Bunuel wrote:

The figure above represents a right circular cylindrical tube made out of paper. The circumference of each circular base is 10 centimeters, the length of AB is 12 centimeters, and BD is a diameter of a base. If the tube is cut along AB, opened and flattened, what is the length of AD in centimeters?

(A) 13
(B) 17
(C) 22
(D) 2√61
(E) √146.5

Attachment:
2017-12-08_1440_002.png

When you cut along AB and open it, you get a rectangle. Notice that in this rectangle, A is on the corner and D is in the centre of the opposite edge. So ABD will form a right triangle.

AB^2 + BD^2 = AD^2

AB is simply the length of the tube at 12 cm but notice what BD is. It is half the circumference of the circular base (since it is opened and flattened) which is 10 cm. So BD = 10/2 = 5 cm

This will be a 5-12-13 triangle then and AD will be 13 cm.

Answer (A)
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8883
Location: Pune, India
Re: The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

08 Dec 2017, 20:15
1
VeritasPrepKarishma wrote:
Bunuel wrote:

The figure above represents a right circular cylindrical tube made out of paper. The circumference of each circular base is 10 centimeters, the length of AB is 12 centimeters, and BD is a diameter of a base. If the tube is cut along AB, opened and flattened, what is the length of AD in centimeters?

(A) 13
(B) 17
(C) 22
(D) 2√61
(E) √146.5

Attachment:
The attachment 2017-12-08_1440_002.png is no longer available

When you cut along AB and open it, you get a rectangle. Notice that in this rectangle, A is on the corner and D is in the centre of the opposite edge. So ABD will form a right triangle.

AB^2 + BD^2 = AD^2

AB is simply the length of the tube at 12 cm but notice what BD is. It is half the circumference of the circular base (since it is opened and flattened) which is 10 cm. So BD = 10/2 = 5 cm

This will be a 5-12-13 triangle then and AD will be 13 cm.

Answer (A)

Responding to a pm:

Quote:
Can you help me understand how BD is half the circumference of the circular base. I am unable to visualize and hence not getting the point.

Here is the original roll.

Attachment:

Rectangular Roll Original.jpg [ 11.96 KiB | Viewed 719 times ]

When you open it, this is what it looks like.

Attachment:

Rectangular Roll.jpg [ 14.09 KiB | Viewed 720 times ]

_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

Intern
Joined: 19 Aug 2017
Posts: 24
Re: The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

22 Dec 2017, 05:48
1
Got the answer to be A

Can anyone explain how it is D??
Math Expert
Joined: 02 Sep 2009
Posts: 52971
Re: The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

22 Dec 2017, 05:57
1
MSarmah wrote:
Got the answer to be A

Can anyone explain how it is D??

The correct answer is A. Edited. Thank you.
_________________
Intern
Joined: 19 Aug 2017
Posts: 24
Re: The figure above represents a right circular cylindrical tube made out  [#permalink]

### Show Tags

22 Dec 2017, 06:06
Bunuel wrote:
MSarmah wrote:
Got the answer to be A

Can anyone explain how it is D??

The correct answer is A. Edited. Thank you.

Welcome Brunnel
Re: The figure above represents a right circular cylindrical tube made out   [#permalink] 22 Dec 2017, 06:06
Display posts from previous: Sort by

# The figure above represents a right circular cylindrical tube made out

 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®.