A BATCH OF COOKIES

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figs: Senior | Next Rank: 100 Posts; Posts: 70; Joined: Mon Mar 30, 2009 9:00 am; Thanked: 2 times

by figs » Tue Apr 28, 2009 1:55 pm

A batch of cookies was divided among three tins: 2/3 of all the cookies were places in either the blue tin or the green tin, and the rest were placed in the red tin. if 1/4 of all the cookies were placed in the blue tin, what fraction of the cookies that were placed in the green or red tins were placed in the green tin?

A: 5/12
B:4/9
C:5/9
D:5/7
E:7/9

OA:C

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Source: Beat The GMAT — Problem Solving | Tue Apr 28, 2009 1:55 pm

dmateer25: Community Manager; Posts: 1049; Joined: Sun Apr 06, 2008 5:15 pmFollowed by: 27 members; Location: Pittsburgh, PA; Thanked: 113 times; GMAT Score:710

by dmateer25 » Tue Apr 28, 2009 2:02 pm

Let’s say there are 12 cookies.

¼ are in the blue tin. So the blue tin has 3.
1/3 are in the red tin. So the red tin has 4.
2/3 – 1/4 = 5/12 are in the green tin. So 5/12 * 12 = 5.

Blue = 3
Red = 4
Green = 5

Now, what fraction of the cookies that were placed in the green or red tins were placed in the green tin

X(4+5) = 5
X= 5/9

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marcusking: Master | Next Rank: 500 Posts; Posts: 106; Joined: Wed Feb 04, 2009 6:09 am; Location: Louisville, KY; Thanked: 8 times

by marcusking » Wed Apr 29, 2009 8:42 am

dmateer25 wrote:Let’s say there are 12 cookies.

¼ are in the blue tin. So the blue tin has 3.
1/3 are in the red tin. So the red tin has 4.
2/3 – 1/4 = 5/12 are in the green tin. So 5/12 * 12 = 5.

Blue = 3
Red = 4
Green = 5

Now, what fraction of the cookies that were placed in the green or red tins were placed in the green tin

X(4+5) = 5
X= 5/9

Perfect! I arrived at the answer the same way.

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kanha81: Master | Next Rank: 500 Posts; Posts: 431; Joined: Sat Jan 10, 2009 9:32 amFollowed by: 1 member; Thanked: 16 times

Re: A BATCH OF COOKIES

by kanha81 » Thu Apr 30, 2009 9:50 am

figs wrote:A batch of cookies was divided among three tins: 2/3 of all the cookies were places in either the blue tin or the green tin, and the rest were placed in the red tin. if 1/4 of all the cookies were placed in the blue tin, what fraction of the cookies that were placed in the green or red tins were placed in the green tin?

A: 5/12
B:4/9
C:5/9
D:5/7
E:7/9

OA:C

Easiet way to solve such problems is pick a number. Notice the denominators like 3, 4.

Let's choose n: number of cookies = 12
b:blue tin
g: green tin
r: red tin

b+g = 2/3 * (12) = 8 cookies
remaining = 12-8 = 4 cookies

r = 1/3 * (12) = 4 cookies (same as remaining cookies)

b = 1/4 * (12) = 3 cookies => g = 5 cookies

x: fraction
(g+r) * x = g
9 * x = 5 => x = 5/9

Hope that helps.

Want to Beat GMAT.
Always do what you're afraid to do. Whoooop GMAT

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mike22629: Master | Next Rank: 500 Posts; Posts: 322; Joined: Fri Mar 27, 2009 3:56 pm; Thanked: 24 times; GMAT Score:710

by mike22629 » Thu Apr 30, 2009 10:15 am

Using ratios is the quickest:

b + g = 2/3 of total
r = 1/3 of total

b = 1/4,

1/4 + g = 2/3
g = 5/12

5/12 + 1/3 = 9/12 ( which is green and red tin)

So to find ratio of green in that

(5/12)/(9/12) = 5/9

This is prolly quickest

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rahul.s: Master | Next Rank: 500 Posts; Posts: 324; Joined: Thu Dec 24, 2009 6:29 amFollowed by: 1 member; Thanked: 17 times

by rahul.s » Mon Jan 25, 2010 10:09 am

dmateer25 wrote:Letï¿½s say there are 12 cookies.

ï¿½ are in the blue tin. So the blue tin has 3.
1/3 are in the red tin. So the red tin has 4.
2/3 ï¿½ 1/4 = 5/12 are in the green tin. So 5/12 * 12 = 5.

Blue = 3
Red = 4
Green = 5

Now, what fraction of the cookies that were placed in the green or red tins were placed in the green tin

X(4+5) = 5
X= 5/9

yeah, i used the exact same method and numbers. it's was a little difficult to interpret at first, but turned out to be quite simple

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crowolta: Newbie | Next Rank: 10 Posts; Posts: 9; Joined: Thu May 20, 2010 5:46 pm; GMAT Score:600

by crowolta » Thu May 20, 2010 5:52 pm

Hi Figs

This is a old discussion and I hope that you check this thread and help me understand one problem.

I saw this question about Tins in Kaplan Gmat 800, but I was confused with the question because the question read something like this

"what fraction of the cookies that were placed in the other tins were placed in the Green Tin/"

Reading this i tried to do (no. of cookies in green tin)/(no. of cookies in blue Tin + No of cookies in red tin). So my answer was wrong. Was this the same question rephrased by you or you interpreted that way. help to understand how to interprete it the way you did.

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ezhilkumarank: Moderator; Posts: 92; Joined: Sat Feb 21, 2009 1:20 amFollowed by: 1 member; Thanked: 5 times

by ezhilkumarank » Sat Sep 18, 2010 4:34 pm

crowolta wrote:Hi Figs

This is a old discussion and I hope that you check this thread and help me understand one problem.

I saw this question about Tins in Kaplan Gmat 800, but I was confused with the question because the question read something like this

"what fraction of the cookies that were placed in the other tins were placed in the Green Tin/"

Reading this i tried to do (no. of cookies in green tin)/(no. of cookies in blue Tin + No of cookies in red tin). So my answer was wrong. Was this the same question rephrased by you or you interpreted that way. help to understand how to interprete it the way you did.

I was searching for the answer to this question and stumbled upon this post. I had the same doubt as you. I believe the question is incorrectly worded in the Kaplan GMAT 800 [2007-2008] edition.

"The will-to-do achieves the deed, when the mind that wills is strong indeed"

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rahuldbhagat: Newbie | Next Rank: 10 Posts; Posts: 3; Joined: Thu Nov 04, 2010 4:26 am

by rahuldbhagat » Thu Nov 18, 2010 2:16 am

I think following is correct question.

"A batch of cookies was divided among three tins: 2/3 of all the cookies were places in either the blue tin or the green tin, and the rest were placed in the red tin. if 1/4 of all the cookies were placed in the blue tin, what fraction of the cookies that were placed in the green or red tins were placed in the green tin? "

So here what we are asked is , G/(G+R) and answer is C:5/9

This problem is mistakenly printed in many Kaplan books. I have Kaplan GMAT Advanced book 2009-2010 edition, in that the question is written as follows

"A batch of cookies was divided among three tins: 2/3 of all the cookies were places in either the blue tin or the green tin, and the rest were placed in the red tin. if 1/4 of all the cookies were placed in the blue tin, what fraction of the cookies that were placed in other tins were placed in the green tin?"

Here it implies that we are asked G/(B+R) giving answer as D: 5/7

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