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

 It is currently 21 Oct 2019, 05:37

### 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

# Danny and Ian are munching on a jar full of candies. Had Dan

Author Message
TAGS:

### Hide Tags

Manager
Joined: 05 Nov 2012
Posts: 138
Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

Updated on: 20 Dec 2012, 02:32
9
7
00:00

Difficulty:

65% (hard)

Question Stats:

50% (01:14) correct 50% (01:12) wrong based on 538 sessions

### HideShow timer Statistics

Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

Source: HULT

Originally posted by Amateur on 19 Dec 2012, 23:40.
Last edited by Bunuel on 20 Dec 2012, 02:32, edited 1 time in total.
Edited the question.
Manager
Joined: 05 Nov 2012
Posts: 138
Re: Danny and Ian are munching on a jar full of candies.  [#permalink]

### Show Tags

19 Dec 2012, 23:42
1
I thought it should be inverse of the combined rates which is (10*5)/(10+5)=50/15=3+ minutes right? OA says a different one.... what am I doing wrong?
Director
Joined: 25 Apr 2012
Posts: 660
Location: India
GPA: 3.21
Re: Danny and Ian are munching on a jar full of candies.  [#permalink]

### Show Tags

19 Dec 2012, 23:52
1
Amateur wrote:
Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar.
Since both of them are eating simultaneously, how long would it take them to empty the jar?

2.5 minutes

3 minutes

3 minutes and 20 seconds

6 minutes and 40 seconds

4 minutes

Source: HULT

Hi,

Danny's does in 5 minutes
Ian finishes half in 10 minutes i.e finishes the jar in 20 minutes

Therefore Combined rate will be

1/5+1/20=1/T

5/20= 1/T ==> T = 4 min
_________________

“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”
Math Expert
Joined: 02 Sep 2009
Posts: 58421
Re: Danny and Ian are munching on a jar full of candies.  [#permalink]

### Show Tags

20 Dec 2012, 02:36
1
1
Amateur wrote:
I thought it should be inverse of the combined rates which is (10*5)/(10+5)=50/15=3+ minutes right? OA says a different one.... what am I doing wrong?

We are told that Ian needs 10 minutes to finish HALF the jar, so he needs 20 minute to finish full jar.

Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

The rate of Danny is 1/5 jar/minute and the rate of Ian is 1/20 jar/minute, their combined rate is 1/5+1/20=1/4 jar/minute. Thus together they need 4 minutes to finish the jar.

_________________
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 15294
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

28 Feb 2015, 14:15
1
Hi All,

This question is essentially a "Work Formula" question, since it has 2 people working on a task together. You have to be really careful with the details though, since the two given rates are NOT for the same task....

We're told that Danny can finish off the jar of candies in 5 minutes
We're told that Ian can finish off HALF the jar of candies in 10 minutes, which means that he can finish the WHOLE jar in 20 minutes.

We're asked how long it would take the two of them to finish the jar of candies together....

Work = (A)(B)/(A+B) where A and B are the individual rates of the two entities.

A = 5
B = 20

(5)(20)/(5+20) = 100/25 = 4 minutes to finish off the jar of candies.

GMAT assassins aren't born, they're made,
Rich
_________________
Contact Rich at: Rich.C@empowergmat.com

The Course Used By GMAT Club Moderators To Earn 750+

souvik101990 Score: 760 Q50 V42 ★★★★★
ENGRTOMBA2018 Score: 750 Q49 V44 ★★★★★
Retired Moderator
Joined: 29 Apr 2015
Posts: 822
Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE: Asset Management (Investment Banking)
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

16 Jul 2015, 02:03
Bunuel wrote:
Amateur wrote:
I thought it should be inverse of the combined rates which is (10*5)/(10+5)=50/15=3+ minutes right? OA says a different one.... what am I doing wrong?

We are told that Ian needs 10 minutes to finish HALF the jar, so he needs 20 minute to finish full jar.

Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

The rate of Danny is 1/5 jar/minute and the rate of Ian is 1/20 jar/minute, their combined rate is 1/5+1/20=1/4 jar/minute. Thus together they need 4 minutes to finish the jar.

OMG, actually this is a very simple question - the only problem here: if you go too fast and ignore the details, you will fail! (Finish HALF the jar...). With this trap this question becomes a 700+ question?!
_________________
Saving was yesterday, heat up the gmatclub.forum's sentiment by spending KUDOS!

PS Please send me PM if I do not respond to your question within 24 hours.
Intern
Joined: 11 Aug 2013
Posts: 24
Location: India
Concentration: Finance, General Management
GMAT 1: 620 Q47 V28
GPA: 3.23
WE: Information Technology (Investment Banking)
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

18 Jul 2015, 09:32
this is a straight forward rate question
Rate of danny finishing the jar = 1/5 J/min
Rate of Ian finishing the jar = 1/20 J/min.

when both eating together = (1/5 +1/20) J/min =>1/4 J/min
Hence they can together eat the whole jar in 4 mins
_________________
Thanks
----------------
Click +1 Kudos if my post helped...
Retired Moderator
Joined: 29 Apr 2015
Posts: 822
Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE: Asset Management (Investment Banking)
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

23 Jul 2015, 21:38
Amateur wrote:
Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

Source: HULT

Plug in a good number for the number of candies. E.g. 10 and set up a rate work table:

Danny: Rate 2 / Time 5 / Work 10
Ian: Rate 0.5 / Time 10 / Work 5
Combined Rate: 2.5 / Time 4 / Work 10

_________________
Saving was yesterday, heat up the gmatclub.forum's sentiment by spending KUDOS!

PS Please send me PM if I do not respond to your question within 24 hours.
SVP
Joined: 26 Mar 2013
Posts: 2344
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

13 Mar 2018, 16:33
Amateur wrote:
Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

Source: HULT

Lot of way to solve but it is not 700 question.

Danny's time to eat = 5 min & Ian's time to eat = 20 min

With number sense, Dan is faster than Ian by 4 times....So it ill take him slightly less 5 minute to finish the candy jar.

Let number of candies =20

Rate of Danny = 20/5 =4
Rate pf Ian = 20/20 =1

rate * time =work

5 * T =20....T = 4 minutes

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8117
Location: United States (CA)
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

27 Jan 2019, 19:35
1
Amateur wrote:
Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

Danny’s rate is 1/5, and Ian’s rate is (1/2)/10. Thus, their combined rate is:

1/5 + (1/2)/10 = 1/5 + 1/20 = 4/20 + 1/20 = 5/20 = 1/4

So it would take them 1/(1/4) = 4 minutes to eat the whole jar of candies together.

_________________

# 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

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Intern
Joined: 10 Jul 2016
Posts: 44
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

27 Jan 2019, 21:36
Amateur wrote:
Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

Source: HULT

Simple formula to be used for work rate problems - Rate * Time = Work

Whenever, work isnt specified - we can imagine it to be = 1

Using the formula - Danny's rate * 5minutes = 1, so danny/s rate = 1/5

Ian's rate * 10 = 1/2, so Ian/s rate = 1/20

The rate together would be 1/5 + 1/20 = 5/20 = 1/4

Hence, (rate together) * time = 1

1/4 * time = 1

Time = 4 minutes.

Intern
Joined: 10 Jul 2016
Posts: 44
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

27 Jan 2019, 21:37
ScottTargetTestPrep wrote:
Amateur wrote:
Danny and Ian are munching on a jar full of candies. Had Danny eaten alone it would have taken him 5 minutes to finish the candies in the jar. Had Ian eaten alone it would have taken him 10 minutes to finish half the jar. Since both of them are eating simultaneously, how long would it take them to empty the jar?

A. 2.5 minutes
B. 3 minutes
C. 3 minutes and 20 seconds
D. 6 minutes and 40 seconds
E. 4 minutes

Danny’s rate is 1/5, and Ian’s rate is (1/2)/10. Thus, their combined rate is:

1/5 + (1/2)/10 = 1/5 + 1/20 = 4/20 + 1/20 = 5/20 = 1/4

So it would take them 1/(1/4) = 4 minutes to eat the whole jar of candies together.

I've always had problems with work rate problems - but you guy have made it so simple for me, Scott. TTP is AWESOME!!
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8117
Location: United States (CA)
Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

### Show Tags

31 Jan 2019, 18:23
Thank you! Glad we could help!
_________________

# 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

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Re: Danny and Ian are munching on a jar full of candies. Had Dan   [#permalink] 31 Jan 2019, 18:23
Display posts from previous: Sort by