Last visit was: 18 Nov 2025, 22:34 It is currently 18 Nov 2025, 22:34
Home
GMAT
Messages
Tests
Schools
Events
Rewards
Chat
My Profile
Close
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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
705-805 Level|   Geometry|      
User avatar
EvaJager
User avatar
Joined: 22 Mar 2011
Last visit: 31 Aug 2016
Posts: 514
Own Kudos:
2,325
 [37]
Given Kudos: 43
WE:Science (Education)
Posts: 514
Kudos: 2,325
 [37]
Helga and Rob like corn on cob. Each prefers to eat the gene 06 Aug 2012, 05:46
5
Kudos
Add Kudos
32
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

85% (hard)

Question Stats:

52% (02:45) correct 48% (02:32) wrong based on 226 sessions

History

Date
Time
Result
Not Attempted Yet
Helga and Rob like corn on the cob. Each prefers to eat the genetically modified type corn, which has perfect cylindrical shape.
Helga likes to eat her corn by chewing circular strips of equal width. Rob prefers to go along the height of the cylinder, munching straight strips of the same width as Helga's strips. If Helga eats half as many circular strips as Rob eats straight strips, what is the ratio between the height and the radius of the corn on the cob?

\((A)\, 1:2\)
\((B)\, 2:1\)
\((C)\, 1:\pi\)
\((D)\, \pi:1\)
\((E)\, 1:\sqrt{\pi}\)
ShowHide Answer
Official Answer
D
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 18 Nov 2025
Posts: 105,356
Own Kudos:
778,104
 [16]
Given Kudos: 99,966
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,356
Kudos: 778,104
 [16]
Helga and Rob like corn on cob. Each prefers to eat the gene 06 Aug 2012, 06:04
5
Kudos
Add Kudos
10
Bookmarks
Bookmark this Post
EvaJager
Helga and Rob like corn on cob. Each prefers to eat the genetically modified type corn, which has perfect cylindrical shape.
Helga likes to eat her corn by chewing circular strips of equal width. Rob prefers to go along the height of the cylinder, munching straight strips of the same width as Helga's strips. If Helga eats half as many circular strips as Rob eats straight strips, what is the ratio between the height and the radius of the corn on cob?

\((A)\, 1:2\)
\((B)\, 2:1\)
\((C)\, 1:\pi\)
\((D)\, \pi:1\)
\((E)\, 1:\sqrt{\pi}\)
Show more

Say the the width of the strip each eats is \(x\).

Since Helga eats the corn circularly, then the number of strips she eats is \(\frac{h}{x}\).
Since Rob eats the corn along the height, then the number of strips he eats is \(\frac{2\pi{r}}{x}\).

We are told that \(\frac{h}{x}=\frac{1}{2}*\frac{2\pi{r}}{x}\) --> \(\frac{h}{r}=\pi\).

Answer: D.
General Discussion
avatar
holidevil
avatar
Joined: 22 Feb 2010
Last visit: 23 Jun 2021
Posts: 27
Own Kudos:
83
 [1]
Given Kudos: 1
Posts: 27
Kudos: 83
 [1]
Helga and Rob like corn on cob. Each prefers to eat the gene 17 Aug 2012, 20:55
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
EvaJager
Helga and Rob like corn on cob. Each prefers to eat the genetically modified type corn, which has perfect cylindrical shape.
Helga likes to eat her corn by chewing circular strips of equal width. Rob prefers to go along the height of the cylinder, munching straight strips of the same width as Helga's strips. If Helga eats half as many circular strips as Rob eats straight strips, what is the ratio between the height and the radius of the corn on cob?

\((A)\, 1:2\)
\((B)\, 2:1\)
\((C)\, 1:\pi\)
\((D)\, \pi:1\)
\((E)\, 1:\sqrt{\pi}\)

Say the the width of the strip each eats is \(x\).

Since Helga eats the corn circularly, then the number of strips she eats is \(\frac{h}{x}\).
Since Rob eats the corn along the height, then the number of strips he eats is \(\frac{2\pi{r}}{x}\).

We are told that \(\frac{h}{x}=\frac{1}{2}*\frac{2\pi{r}}{x}\) --> \(\frac{h}{r}=\pi\).

Answer: D.
Show more

Please explain how you obtained the number of strips eaten by each of them; how was the equality obtained? How can we use the information about the way of their eating corn to determine the number of strips eaten by each of them.
User avatar
saikarthikreddy
User avatar
Joined: 19 Apr 2011
Last visit: 14 Feb 2022
Posts: 128
Own Kudos:
1,037
 [2]
Given Kudos: 53
Concentration: Finance,Entrepreneurship,General Management
Schools: Carlson '16 (I) Kelley '16 (I) Tuck '16 (D) Darden '24 (II)
GMAT 1: 720 Q49 V38
GRE 1: Q167 V167
Posts: 128
Kudos: 1,037
 [2]
Helga and Rob like corn on cob. Each prefers to eat the gene 20 Aug 2012, 10:51
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The circumference of the cylinder is 2*pi*r.
Dividing by x gives the number of vertical strips ,because each strip is of width x.
The height of the cylinder is h.Dividing by x will give you the number of horizontal strips.
Now apply the data given in the question and equate.
Hope this helps .
User avatar
GyMrAT
User avatar
Joined: 14 Dec 2017
Last visit: 03 Nov 2020
Posts: 412
Own Kudos:
509
 [2]
Given Kudos: 173
Location: India
Posts: 412
Kudos: 509
 [2]
Helga and Rob like corn on cob. Each prefers to eat the gene 08 Jun 2018, 01:18
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
EvaJager
Helga and Rob like corn on the cob. Each prefers to eat the genetically modified type corn, which has perfect cylindrical shape.
Helga likes to eat her corn by chewing circular strips of equal width. Rob prefers to go along the height of the cylinder, munching straight strips of the same width as Helga's strips. If Helga eats half as many circular strips as Rob eats straight strips, what is the ratio between the height and the radius of the corn on the cob?

\((A)\, 1:2\)
\((B)\, 2:1\)
\((C)\, 1:\pi\)
\((D)\, \pi:1\)
\((E)\, 1:\sqrt{\pi}\)
Show more


Let r be the radius & h be the height of the cylindrical corn cob.

Total Curved Surface Area = \(2*\pi*r*h\)

Let \(a\) be the width of each strip.

Curved Surface Area of each strip eaten by Helga = \(2*\pi*r*a\)

Hence # of strips eaten by Helga, \(S_h\) = \((2*\pi*r*h)\)/\((2*\pi*r*a)\) = \(h/a\)

Area of each strip eaten by Rob = \(h * a\)

Hence # of Strips eaten by Rob, \(S_r\) = \(2*\pi*r*h\)/\(h * a\) = \(2*\pi*r/a\)

Now given that, \(S_h\) = \({S_r}/2\)

Hence, \(h/a\) = \(2*\pi*r/{2a}\)

Simplified as, \(h/r\) = \(\pi\)

Answer D.

Thanks,
GyM
avatar
gyanamaya
avatar
Joined: 31 Mar 2018
Last visit: 08 Feb 2022
Posts: 6
Own Kudos:
3
Given Kudos: 630
Location: India
Schools: ISB '23
GMAT 1: 650 Q48 V34
Schools: ISB '23
GMAT 1: 650 Q48 V34
Posts: 6
Kudos: 3
Helga and Rob like corn on cob. Each prefers to eat the gene 23 Jun 2019, 08:13
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
EvaJager
Helga and Rob like corn on cob. Each prefers to eat the genetically modified type corn, which has perfect cylindrical shape.
Helga likes to eat her corn by chewing circular strips of equal width. Rob prefers to go along the height of the cylinder, munching straight strips of the same width as Helga's strips. If Helga eats half as many circular strips as Rob eats straight strips, what is the ratio between the height and the radius of the corn on cob?

\((A)\, 1:2\)
\((B)\, 2:1\)
\((C)\, 1:\pi\)
\((D)\, \pi:1\)
\((E)\, 1:\sqrt{\pi}\)

Say the the width of the strip each eats is \(x\).

Since Helga eats the corn circularly, then the number of strips she eats is \(\frac{h}{x}\).
Since Rob eats the corn along the height, then the number of strips he eats is \(\frac{2\pi{r}}{x}\).

We are told that \(\frac{h}{x}=\frac{1}{2}*\frac{2\pi{r}}{x}\) --> \(\frac{h}{r}=\pi\).

Answer: D.
Show more

I have a doubt here.How did you come to know that the rob's number of strips will be 2*pi*r/x ? We dont know how the strips are being cut here.It will be 2r/x if the strips are cut from a circle side wise. if the strips are cut till the center then it will be 2*pi*r/x.Please expain.
User avatar
ScottTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 14 Oct 2015
Last visit: 18 Nov 2025
Posts: 21,712
Own Kudos:
26,991
 [2]
Given Kudos: 300
Status:Founder & CEO
Affiliations: Target Test Prep
Location: United States (CA)
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 21,712
Kudos: 26,991
 [2]
Helga and Rob like corn on cob. Each prefers to eat the gene 02 Sep 2020, 07:19
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
EvaJager
Helga and Rob like corn on the cob. Each prefers to eat the genetically modified type corn, which has perfect cylindrical shape.
Helga likes to eat her corn by chewing circular strips of equal width. Rob prefers to go along the height of the cylinder, munching straight strips of the same width as Helga's strips. If Helga eats half as many circular strips as Rob eats straight strips, what is the ratio between the height and the radius of the corn on the cob?

\((A)\, 1:2\)
\((B)\, 2:1\)
\((C)\, 1:\pi\)
\((D)\, \pi:1\)
\((E)\, 1:\sqrt{\pi}\)
Show more
Solution:

Let the radius and height of the cob be r and h, respectively. Let the number of circular strips Helga eats be n. Then, Rob eats 2n straight strips.

Let the width of each circular strip and each horizontal strip be w. Then, the height of the cob is nw and the circumference of the base is 2nw. We have:

h = nw

2?r = 2nw

From the second equation, we obtain nw = ?r. Substituting nw = h, we obtain h = ?r. Thus, h/r = ?. The ratio of the height to the radius is ? : 1.

Answer: D
User avatar
Crytiocanalyst
User avatar
Joined: 16 Jun 2021
Last visit: 27 May 2023
Posts: 950
Own Kudos:
208
Given Kudos: 309
Posts: 950
Kudos: 208
Helga and Rob like corn on cob. Each prefers to eat the gene 06 Feb 2022, 01:02
Kudos
Add Kudos
Bookmarks
Bookmark this Post
EvaJager
Helga and Rob like corn on the cob. Each prefers to eat the genetically modified type corn, which has perfect cylindrical shape.
Helga likes to eat her corn by chewing circular strips of equal width. Rob prefers to go along the height of the cylinder, munching straight strips of the same width as Helga's strips. If Helga eats half as many circular strips as Rob eats straight strips, what is the ratio between the height and the radius of the corn on the cob?

\((A)\, 1:2\)
\((B)\, 2:1\)
\((C)\, 1:\pi\)
\((D)\, \pi:1\)
\((E)\, 1:\sqrt{\pi}\)
Show more

let the height and width be H and w

1/2 * 2*pi *r *w = H* w
=> H/r =pi

THerefore IMO D
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,584
Own Kudos:
1,079
Posts: 38,584
Kudos: 1,079
Helga and Rob like corn on cob. Each prefers to eat the gene 31 Jul 2023, 17:30
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Bunuel
Math Expert
105356 posts
Krunaal
Tuck School Moderator
805 posts