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If the total price for n copies of a book is $31.50, what is the price

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If the total price for n copies of a book is $31.50, what is the price  [#permalink]

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New post 03 Apr 2017, 12:44
3
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A
B
C
D
E

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Question Stats:

68% (02:12) correct 32% (01:49) wrong based on 112 sessions

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If the total price for n copies of a book is $31.50, what is the price per copy of the book?

(1) If twice as many copies were bought for the same total price, the price per copy would be $1.75.
(2) If 4 fewer copies were bought for the same total price, the price per copy would be $2.80 greater.

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Re: If the total price for n copies of a book is $31.50, what is the price  [#permalink]

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New post 13 Jun 2017, 07:54
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abhishekdadarwal2009 wrote:
If the total price for n copies of a book is $31.50, what is the price per copy of the book?

(1) If twice as many copies were bought for the same total price, the price per copy would be $1.75.
(2) If 4 fewer copies were bought for the same total price, the price per copy would be $2.80 greater.

The Cost of per copy =31.50/n

1.31.50/2n=1.75 therefore we can easility find n.

2.31.50/(n-4)=2.80 , Therefore n can be found easily.

D is the correct answer because we can find the answer from both A and B independently.


Hi,

Actually the equation you have written for the second statement is wrong.
S2 says that price per copy would increase by $2.8 but your equation means price per copy becomes $2.8.

So the correct equation is as follows

Initial price per copy = 31.5/n
New price per copy = 31.5/(n-4) = 31.5/n + 2.8
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Re: If the total price for n copies of a book is $31.50, what is the price  [#permalink]

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New post 05 Apr 2017, 10:16
If the total price for n copies of a book is $31.50, what is the price per copy of the book?

(1) If twice as many copies were bought for the same total price, the price per copy would be $1.75.
(2) If 4 fewer copies were bought for the same total price, the price per copy would be $2.80 greater.

The Cost of per copy =31.50/n

1.31.50/2n=1.75 therefore we can easility find n.

2.31.50/(n-4)=2.80 , Therefore n can be found easily.

D is the correct answer because we can find the answer from both A and B independently.
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Re: If the total price for n copies of a book is $31.50, what is the price  [#permalink]

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New post 13 Jun 2017, 15:09
Statement 2 is sufficient because we can use substitution and solve for the remaining variable, correct?
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Re: If the total price for n copies of a book is $31.50, what is the price  [#permalink]

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New post 14 Jun 2017, 08:01
Smokeybear00 wrote:
Statement 2 is sufficient because we can use substitution and solve for the remaining variable, correct?


Hi,

Not sure what you mean by substitution here.
You will actually get a quadratic equation here. With values of n=9 and n=-5, since n cannot be negative, thus n=9. Hence sufficient.

Hope it helps.
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If the total price for n copies of a book is $31.50, what is the price  [#permalink]

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New post 14 Jun 2017, 09:16
nitred wrote:
Smokeybear00 wrote:
Statement 2 is sufficient because we can use substitution and solve for the remaining variable, correct?


Hi,

Not sure what you mean by substitution here.
You will actually get a quadratic equation here. With values of n=9 and n=-5, since n cannot be negative, thus n=9. Hence sufficient.

Hope it helps.


I mean since we now know \(p=\frac{31.50}{n-4}-2.80\) we can use that in the original equation in place of P, thus solving for n
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Re: If the total price for n copies of a book is $31.50, what is the price  [#permalink]

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New post 06 Jul 2017, 17:19
SajjadAhmad wrote:
If the total price for n copies of a book is $31.50, what is the price per copy of the book?

(1) If twice as many copies were bought for the same total price, the price per copy would be $1.75.
(2) If 4 fewer copies were bought for the same total price, the price per copy would be $2.80 greater.


We need to determine 31.5/n.

Statement One Alone:

If twice as many copies were bought for the same total price, the price per copy would be $1.75.

We can create the following equation:

(2n)(1.75) = 31.50

2n = 18

9 = n

Thus, 31.5/9 = $3.50. Statement one alone is sufficient to answer the question.

Statement Two Alone:

If 4 fewer copies were bought for the same total price, the price per copy would be $2.80 greater.

We can create the following equation:

31.50/(n - 4) = 31.50/n + 2.80

We see that we have enough information to determine n and thus enough information to determine the price per copy. Statement two alone is sufficient to answer the question.

Answer: D
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Re: If the total price for n copies of a book is $31.50, what is the price   [#permalink] 06 Jul 2017, 17:19
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