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chaitanyareddy: Senior | Next Rank: 100 Posts; Posts: 30; Joined: Fri Feb 27, 2009 12:45 am; Thanked: 1 times; GMAT Score:620

number of books

by chaitanyareddy » Wed Nov 10, 2010 5:34 am

Store S sold a total of 90 copies of a certain book during the seven days last week and it sold different number of copies on any two days of the week. If in a week , Store S sold a greatest number of copies on saturday and the second greatest on friday , Did the store sell more than 11 copies on friday.

1)The store sold 8 copies on thursday last week.
2)The store sold 38 copies on saturday , last week.

Even the word Impossible says I'Mpossible.

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Source: Beat The GMAT — Data Sufficiency | Wed Nov 10, 2010 5:34 am

beat_gmat_09: Master | Next Rank: 500 Posts; Posts: 437; Joined: Sat Nov 22, 2008 5:06 am; Location: India; Thanked: 50 times; Followed by:1 members; GMAT Score:580

by beat_gmat_09 » Wed Nov 10, 2010 6:24 am

chaitanyareddy wrote:Store S sold a total of 90 copies of a certain book during the seven days last week and it sold different number of copies on any two days of the week. If in a week , Store S sold a greatest number of copies on saturday and the second greatest on friday , Did the store sell more than 11 copies on friday.

1)The store sold 8 copies on thursday last week.
2)The store sold 38 copies on saturday , last week.

This is how i tried.
Total no of books in a week = 90
In that week, two days different no of books. Therefore 5x + S + F = 90
Where x = no of books sold on days other than Sat and Fri (which is equal to no. of books sold on other days.),
S - Highest no. of books sold, Saturday.
F - Second highest no. of books sold, Friday.
ques - Is F > 11 ?

1) 8 copies sold last week, x = 8, equation becomes = 40 + S + F = 90. S + F = 50.
Not sufficient.

2) 38 Copies sold on Sat. Equation becomes 5x+38+F = 90, 5x + F = 52.
there can be different sets of values for x and F, Not sufficient.

Combine 1 & 2, F = 52 - 40 = 12. F >11.
1 & 2 sufficient. Pick C.

Hope is the dream of a man awake

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selango: Legendary Member; Posts: 1460; Joined: Tue Dec 29, 2009 1:28 am; Thanked: 135 times; Followed by:7 members

by selango » Wed Nov 10, 2010 7:56 am

5a+b+c=90

b and c are different copies.b and c copies are sold on friday and saturday.

Let be C greatest and b be second greatest.

Is b>11?

stmt1,

8 copies on thursday.

-->5*8+b+c=90

b+c=50

b can be 10 or 11.No info abt b.

stmt2,

c=38

5a+b=52

Possible values are,

a=9,b=7

a=10,b=2

The above 2 values are not possible as second greatest copies are sold on friday.

So the only value possible is below,

a=8,b=12

12 copies are sold on Friday.

Sufficient.

Pick B

--Anand--

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goyalsau: Legendary Member; Posts: 866; Joined: Mon Aug 02, 2010 6:46 pm; Location: Gwalior, India; Thanked: 31 times

by goyalsau » Wed Nov 10, 2010 10:02 am

selango wrote:5a+b+c=90

b and c are different copies.b and c copies are sold on friday and saturday.

Let be C greatest and b be second greatest.

Is b>11?

stmt1,

8 copies on thursday.

-->5*8+b+c=90

b+c=50

b can be 10 or 11.No info abt b.

stmt2,

c=38

5a+b=52

Possible values are,

a=9,b=7

a=10,b=2

The above 2 values are not possible as second greatest copies are sold on friday.

So the only value possible is below,

a=8,b=12

12 copies are sold on Friday.

Sufficient.

Pick B

Store S sold a total of 90 copies of a certain book during the seven days last week and it sold different number of copies on any two days of the week. If in a week , Store S sold a greatest number of copies on saturday and the second greatest on friday , Did the store sell more than 11 copies on friday.

How's B is the answer now.
you are taking a single value of a ,
Infect everyday has a different value..

Saurabh Goyal
[email protected]
-------------------------

EveryBody Wants to Win But Nobody wants to prepare for Win.

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avn_0903: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Sat Oct 23, 2010 7:51 pm; Thanked: 1 times

by avn_0903 » Wed Nov 10, 2010 11:49 am

I think when the statement says : "it sold different number of copies on any two days of the week", it meant that no number of books sold on any particular day is the same.

Now here's my answer:

Assume that 11 copies were sold on Friday, that must mean all the other days must have lower and different numbers of copies sold (since Friday is the second greatest). Now try to pick number for the other 5 days (e.g. 6,7,8,9,10) and we can see that no matter what number we pick for those days, the number of copies sold on Saturday must be equal or greater than 39 in order to add up to a total of 90.

The same thing goes for the case of less than 11 copies were sold on Friday, the number of copies sold on Sat must be equal or greater than 39.

However, if the number of copies sold on Friday was greater than 11, the number of copies sold on Sat can both be 39 and greater (40, 12, 11, 9, 8, 7, 3) or 38 and below (37, 15, 10, 9, 8, 7, 4).

Thus we can rephrase the question as: Was the number of copies sold on Sat equal or greater than 39 (in which case the statement would be insufficient) or below 39 (in which case Friday would have to be greater than 11 so that the total number of books add up to 90).

Statement 1:

One of the "less" day is 8 copies => insufficient since from the 3 number picking examples above we can see that Friday can be greater, or equal to 11.

Statement 2:

Sat = 38. Sufficient because now we know Friday would have to be greater than 11 in order for all the days to add up to 90

Answer: B

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beat_gmat_09: Master | Next Rank: 500 Posts; Posts: 437; Joined: Sat Nov 22, 2008 5:06 am; Location: India; Thanked: 50 times; Followed by:1 members; GMAT Score:580

by beat_gmat_09 » Wed Nov 10, 2010 6:41 pm

Its getting confusing.
Please post the OA.
Experts please explain.

Thanks

Hope is the dream of a man awake

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goyalsau: Legendary Member; Posts: 866; Joined: Mon Aug 02, 2010 6:46 pm; Location: Gwalior, India; Thanked: 31 times

by goyalsau » Wed Nov 10, 2010 7:43 pm

avn_0903 wrote:I think when the statement says : "it sold different number of copies on any two days of the week", it meant that no number of books sold on any particular day is the same.

Now here's my answer:

Assume that 11 copies were sold on Friday, that must mean all the other days must have lower and different numbers of copies sold (since Friday is the second greatest). Now try to pick number for the other 5 days (e.g. 6,7,8,9,10) and we can see that no matter what number we pick for those days, the number of copies sold on Saturday must be equal or greater than 39 in order to add up to a total of 90.

The same thing goes for the case of less than 11 copies were sold on Friday, the number of copies sold on Sat must be equal or greater than 39.

However, if the number of copies sold on Friday was greater than 11, the number of copies sold on Sat can both be 39 and greater (40, 12, 11, 9, 8, 7, 3) or 38 and below (37, 15, 10, 9, 8, 7, 4).

Thus we can rephrase the question as: Was the number of copies sold on Sat equal or greater than 39 (in which case the statement would be insufficient) or below 39 (in which case Friday would have to be greater than 11 so that the total number of books add up to 90).

Statement 1:

One of the "less" day is 8 copies => insufficient since from the 3 number picking examples above we can see that Friday can be greater, or equal to 11.

Statement 2:

Sat = 38. Sufficient because now we know Friday would have to be greater than 11 in order for all the days to add up to 90

Answer: B

Very Nicely Explained,
I have learned that it is always good to rephrase a question.
I was not able to do it{Most of the times }, But you did it very Well.
Awesome work...

Saurabh Goyal
[email protected]
-------------------------

EveryBody Wants to Win But Nobody wants to prepare for Win.