Confused by the Ans : pls help ?

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himu: Master | Next Rank: 500 Posts; Posts: 345; Joined: Sun Dec 21, 2008 10:57 pm; Thanked: 6 times; Followed by:3 members

Confused by the Ans : pls help ?

by himu » Sun Mar 17, 2013 5:49 am

Although Grandma's Cookies contain many ingredients, the two main ingredients are sugar and flour. In order for the cookies to turn out properly, these main ingredients must be in proportion to one another. What is the ratio of cups of flour to cups of sugar found in a batch of cookie dough?

In 6 cups of cookie dough, there are 4 cups of flour.
In 13 cups of cookie dough, there are 3 cups of sugar.

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Source: Beat The GMAT — Data Sufficiency | Sun Mar 17, 2013 5:49 am

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Anju@Gurome: GMAT Instructor; Posts: 511; Joined: Wed Aug 11, 2010 9:47 am; Location: Delhi, India; Thanked: 344 times; Followed by:86 members

by Anju@Gurome » Sun Mar 17, 2013 5:59 am

himu wrote:Although Grandma's Cookies contain many ingredients, the two main ingredients are sugar and flour. In order for the cookies to turn out properly, these main ingredients must be in proportion to one another. What is the ratio of cups of flour to cups of sugar found in a batch of cookie dough?

(1) In 6 cups of cookie dough, there are 4 cups of flour.
(2) In 13 cups of cookie dough, there are 3 cups of sugar.

I'm assuming that both statements are talking about the same cookie dough, i.e. the cookie dough for Grandma's Cookies.

The cookie dough may contain some other ingredients apart from flour and sugar. Now, each of the statements individually tells us the ratio of cups of either flour or sugar to the cups of cookie dough. Hence, neither of the statement are individually sufficient to find the ratio of flour to sugar.

1 & 2 Together: Now, we know that in one cup of cookie dough there is 4/6 cups of flour and 3/13 cups of sugar. Hence, ratio of cups of flour to cups of sugar in a batch of cookie dough = (4/6)/(3/13)

Sufficient

The correct answer is C.

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himu: Master | Next Rank: 500 Posts; Posts: 345; Joined: Sun Dec 21, 2008 10:57 pm; Thanked: 6 times; Followed by:3 members

by himu » Mon Mar 18, 2013 3:54 am

Hey Anju,
Thanks for your reply !

but I hv the following doubt, can u pls resolve?

Q asks: What is the ratio of cups of flour to cups of sugar found in a batch of cookie dough?

Statement I :
In 6 cups of cookie dough, there are 4 cups of flour.

so,6 cups of cookie dough(sugar and flour) there are 4 cups of flour.
means :

(sugar + flour)=6 & flour =4

So,
(S+F)/F=6/4

now we can get the ratio.

Similarly Statement II :

In 13 cups of cookie dough, there are 3 cups of sugar.

So,

(S+F)/S=13/3

we can get the ratio.

My ans D = each statement is aloe sufficient.

Pls correct me where I am going wrong.

Thanks & Regards,
~Himu.

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Anju@Gurome: GMAT Instructor; Posts: 511; Joined: Wed Aug 11, 2010 9:47 am; Location: Delhi, India; Thanked: 344 times; Followed by:86 members

by Anju@Gurome » Mon Mar 18, 2013 4:18 am

himu wrote:so,6 cups of cookie dough(sugar and flour) there are 4 cups of flour.
means :

(sugar + flour)=6 & flour =4

The problem said there are many ingredients.
Hence, sugar and flour are always there but there may be some other ingredients also. In fact there are other ingredients otherwise the ratio you obtained should've been same for both he statements.

Hope that helps.

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GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pm; Location: New York, NY; Thanked: 13060 times; Followed by:1906 members; GMAT Score:790

by GMATGuruNY » Mon Mar 18, 2013 4:25 am

himu wrote:Although Grandma's Cookies contain many ingredients, the two main ingredients are sugar and flour. In order for the cookies to turn out properly, these main ingredients must be in proportion to one another. What is the ratio of cups of flour to cups of sugar found in a batch of cookie dough?

In 6 cups of cookie dough, there are 4 cups of flour.
In 13 cups of cookie dough, there are 3 cups of sugar.

Note that flour and sugar the two MAIN ingredients; they are not the ONLY ingredients.

Statement 1:
Flour/total = 4/6 = 2/3.
No way to determine flour/sugar.
INSUFFICIENT.

Statement 2:
Sugar/total = 3/13.
No way to determine flour/sugar.
INSUFFICIENT.

Statements combined:
Flour/sugar = (flour/total) / (sugar/total) = (2/3) / (3/13) = (2/3)(13/3) = 26/9.
SUFFICIENT.

The correct answer is C.

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