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

It is currently 20 Jan 2019, 13:30

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.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar

Grass in pasture grows equally thick and at a uniform rate. It takes 2

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

Hide Tags

 
Manager
Manager
avatar
G
Joined: 29 Nov 2018
Posts: 65
Concentration: Marketing, Strategy
Grass in pasture grows equally thick and at a uniform rate. It takes 2  [#permalink]

Show Tags

New post 13 Jan 2019, 08:49
5
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

14% (01:20) correct 86% (01:09) wrong based on 28 sessions

HideShow timer Statistics

Grass in pasture grows equally thick and at a uniform rate. It takes 24 days for 70 cows to graze the pasture completely. However if there were only 30 cows, they could graze the entire pasture for 60 days. How many cows will graze the entire pasture in 96 days?

(A) 48
(B) 18
(C) 20
(D) 25
(E) 32
VP
VP
User avatar
G
Joined: 18 Aug 2017
Posts: 1253
Location: India
Concentration: Sustainability, Marketing
WE: Marketing (Energy and Utilities)
CAT Tests
Re: Grass in pasture grows equally thick and at a uniform rate. It takes 2  [#permalink]

Show Tags

New post 13 Jan 2019, 09:08
1
cfc198 wrote:
Grass in pasture grows equally thick and at a uniform rate. It takes 24 days for 70 cows to graze the pasture completely. However if there were only 30 cows, they could graze the entire pasture for 60 days. How many cows will graze the entire pasture in 96 days?

(A) 48
(B) 18
(C) 20
(D) 25
(E) 32


cfc198
hi is the question posted correct?
I am getting answer as 18 ..
could you please post solution.
_________________

If you liked my solution then please give Kudos. Kudos encourage active discussions.

Manager
Manager
avatar
G
Joined: 29 Nov 2018
Posts: 65
Concentration: Marketing, Strategy
Grass in pasture grows equally thick and at a uniform rate. It takes 2  [#permalink]

Show Tags

New post 13 Jan 2019, 14:19
Archit3110 wrote:
cfc198 wrote:
Grass in pasture grows equally thick and at a uniform rate. It takes 24 days for 70 cows to graze the pasture completely. However if there were only 30 cows, they could graze the entire pasture for 60 days. How many cows will graze the entire pasture in 96 days?

(A) 48
(B) 18
(C) 20
(D) 25
(E) 32


cfc198
hi is the question posted correct?
I am getting answer as 18 ..
could you please post solution.


when field is grazed in 24 days, we need 24 × 70 i.e. 1680 cow-days
when field is grazed in 60 days, we need 60 × 30 i.e. 1800 cow-days.

Thus, an increase of 36 days necessitated an additional 120 cow-days
If field has to last for 96 days, i.e. a further 36 days (from 60 days), a
further 120 cow-days would be needed. Thus, total cow-days needed for
the field to last 96 days is 1800 + 120 = 1920.

1920 cow-days, with days being 96 implies, the number of cows is

1920/ 96 = 20
VP
VP
User avatar
G
Joined: 18 Aug 2017
Posts: 1253
Location: India
Concentration: Sustainability, Marketing
WE: Marketing (Energy and Utilities)
CAT Tests
Re: Grass in pasture grows equally thick and at a uniform rate. It takes 2  [#permalink]

Show Tags

New post 13 Jan 2019, 22:04
1
cfc198

whats the source of the question..


cfc198 wrote:
Archit3110 wrote:
cfc198 wrote:
Grass in pasture grows equally thick and at a uniform rate. It takes 24 days for 70 cows to graze the pasture completely. However if there were only 30 cows, they could graze the entire pasture for 60 days. How many cows will graze the entire pasture in 96 days?

(A) 48
(B) 18
(C) 20
(D) 25
(E) 32


cfc198
hi is the question posted correct?
I am getting answer as 18 ..
could you please post solution.


when field is grazed in 24 days, we need 24 × 70 i.e. 1680 cow-days
when field is grazed in 60 days, we need 60 × 30 i.e. 1800 cow-days.

Thus, an increase of 36 days necessitated an additional 120 cow-days
If field has to last for 96 days, i.e. a further 36 days (from 60 days), a
further 120 cow-days would be needed. Thus, total cow-days needed for
the field to last 96 days is 1800 + 120 = 1920.

1920 cow-days, with days being 96 implies, the number of cows is

1920/ 96 = 20

_________________

If you liked my solution then please give Kudos. Kudos encourage active discussions.

Manager
Manager
User avatar
G
Joined: 28 Jul 2016
Posts: 212
Location: India
Concentration: Finance, Human Resources
GPA: 3.97
Re: Grass in pasture grows equally thick and at a uniform rate. It takes 2  [#permalink]

Show Tags

New post 20 Jan 2019, 10:35
Bunuel can you please elaborate on the solution.
not very sure of the solution posted
_________________

Please give Kudos. Kudos encourage active discussions and help the community grow

Manager
Manager
avatar
G
Joined: 02 Aug 2015
Posts: 136
Re: Grass in pasture grows equally thick and at a uniform rate. It takes 2  [#permalink]

Show Tags

New post 20 Jan 2019, 11:12
cfc198 wrote:

when field is grazed in 24 days, we need 24 × 70 i.e. 1680 cow-days
when field is grazed in 60 days, we need 60 × 30 i.e. 1800 cow-days.

Thus, an increase of 36 days necessitated an additional 120 cow-days
If field has to last for 96 days, i.e. a further 36 days (from 60 days), a
further 120 cow-days would be needed. Thus, total cow-days needed for
the field to last 96 days is 1800 + 120 = 1920.

1920 cow-days, with days being 96 implies, the number of cows is

1920/ 96 = 20


Hey cfc198

Not only an increase of 36 days, but also a decrease of 40 cows are responsible for the change of 120 cow-days, right?

It takes 24 days for 70 cows - So each cow takes 1/(24*70) days to graze the pasture.
if there were only 30 cows, they could graze the entire pasture for 60 days - Each cow takes 1/(60*30) days to graze the pasture.

The rate of work done by each cow varies in the two given scenarios. Is such variation possible or am I missing something?

Please let us know the source of the question.

Cheers!
Intern
Intern
avatar
B
Joined: 18 Dec 2018
Posts: 2
Re: Grass in pasture grows equally thick and at a uniform rate. It takes 2  [#permalink]

Show Tags

New post 20 Jan 2019, 11:28
I'll attempt to answer this, the method could be completely wrong

We get given in the question that:
70 cows take 24 days
30 cows take 60 days

I solved this problem using ratios

So first I found the ratios of days:

\(\frac{60}{24} = 2.5 \\
\frac{96}{60} = 1.6\)

Now I will calculate the ratio of the cows:

\(\frac{70}{30} = \frac{7}{3} \\
\frac{30}{x} = y\)

Here \(x =\) no. of cows & \(y =\)the ratio between the number of cows.

Here is where my method goes a little weird, so to find \(y\) I worked out the ratio between the two day ratios and then multiplied this by the cow ratio. It's hard to explain but it's logically sound but I'm not amazing with explaining stuff.

\(\frac{1.6}{2.5} = \frac{16}{25} \approx \frac{2}{3}\)

Now multiple this value by the cow ratio:

\(\frac{2}{3} * \frac{7}{3} = \frac{14}{9} \approx 1.5 = y\)

So we have:

\(\frac{30}{x} = y = 1.5 \\
x = 20\)

I probably did this in a super long way but I hope I got it on the right lines ish.
GMAT Club Bot
Re: Grass in pasture grows equally thick and at a uniform rate. It takes 2 &nbs [#permalink] 20 Jan 2019, 11:28
Display posts from previous: Sort by

Grass in pasture grows equally thick and at a uniform rate. It takes 2

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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®.