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

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

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New post Updated on: 20 Dec 2012, 02:32
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  65% (hard)

Question Stats:

48% (01:14) correct 52% (01:12) wrong based on 450 sessions

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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.
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Re: Danny and Ian are munching on a jar full of candies.  [#permalink]

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New post 19 Dec 2012, 23:42
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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?
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Re: Danny and Ian are munching on a jar full of candies.  [#permalink]

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New post 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
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Re: Danny and Ian are munching on a jar full of candies.  [#permalink]

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New post 20 Dec 2012, 02:36
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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.

Answer: E.
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Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

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New post 28 Feb 2015, 14:15
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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.

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Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

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New post 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.

Answer: E.


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?! :roll:
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Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

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New post 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
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Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

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New post 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

Answer E
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Re: Danny and Ian are munching on a jar full of candies. Had Dan  [#permalink]

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New post 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

Answer: E
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Re: Danny and Ian are munching on a jar full of candies. Had Dan &nbs [#permalink] 13 Mar 2018, 16:33
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