OG-10-129-> Explanation is weird

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ash_maverick: Senior | Next Rank: 100 Posts; Posts: 31; Joined: Sun Jan 07, 2007 11:13 pm

by ash_maverick » Mon Jun 29, 2009 10:02 pm

At the beginning of the last month, a stationary store had in stocks 250 writing pads, which had cost the store $0.75 each.During the same month the store made only one purchase of writing pads . What was the total amount spent by the store on the writing pads it had in stock at the end of last months.

1-Last month the store purchased 150 writing pad for $.80 each.

2- Last week the total revenue from the sale of writing pad was $180.

Now, here is the problem i am facing. The Answer says E, but my answer is A.

I found the explanation in 10 OG really weird. See, i have to find the total amount spent on the pad. so i just have to add the amount spent on buying 250 @.75 and 150 @.80. This simply gives me the total amount spent. Now, form where on the earth the other amount comes into picture, the way it has been explained in 10 OG.

can somebody please explain me?

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aj5105: Legendary Member; Posts: 1169; Joined: Sun Jul 06, 2008 2:34 amFollowed by: 1 member; Thanked: 25 times

by aj5105 » Mon Jun 29, 2009 10:23 pm

I am giving this a shot. Experts - correct me if I am wrong.

At the beginning of the last month, a stationary store had in stocks 250 writing pads, which had cost the store $0.75 each.

The above statement does not indicate that the pads were bought in that very month. They could have been carried forward from the previous month or the the other possibility is that the pads had been bought in that month. So, we are not sure here.

What was the total amount spent by the store on the writing pads it had in stock at the end of last months?

we cannot answer the above question unless we know the answer for the previous question.

Hence, (A) cannot be the answer.

(B) doesn't help too.

Hence (E)

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GMATQuantCoach: Senior | Next Rank: 100 Posts; Posts: 44; Joined: Sun Jun 28, 2009 8:58 am; Location: Online; Thanked: 13 times; GMAT Score:51

by GMATQuantCoach » Tue Jun 30, 2009 6:25 am

What was the total amount spent by the store on the writing pads it had in stock at the end of last month

cubicle_bound_misfit is correct. You have no info of the # of writing pads sold last month, so you don't know how many is left in stock.

Last edited by GMATQuantCoach on Tue Jun 30, 2009 9:04 am, edited 1 time in total.

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cubicle_bound_misfit: Master | Next Rank: 500 Posts; Posts: 246; Joined: Mon May 19, 2008 7:34 am; Location: Texaco Gas Station; Thanked: 7 times

by cubicle_bound_misfit » Tue Jun 30, 2009 7:01 am

at the end of last month ------ how do you know how much stock was sold at the end . no stmt highlights that. hence E.

Cubicle Bound Misfit

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shanmugam.d: Junior | Next Rank: 30 Posts; Posts: 29; Joined: Thu Apr 30, 2009 1:32 pm; Thanked: 2 times

by shanmugam.d » Tue Jun 30, 2009 8:38 am

can be formulated as below:

n1 (stock at begining of month) = 250, c1 (cost per pad for the initial stock)= 0.75

n2 (stock purchased during the same month) , c2 (new cost per pad for the new stock)

question is to find the value of stock at the end of the month (if it sells any pads during that month it has to be deducted)
Value of stock = n1xc1 + n2xc2 - (value of sold stock)

(1) n2 & c2 is given but no data for the sold stock, not sufficient
(2) tells about the revenue, no details about n2, c2 and profit margin, not sufficient
even combining both we cant tell the cost of sold stock

Hence (E)

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kessbest: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Wed Jun 10, 2009 10:47 am

by kessbest » Tue Jun 30, 2009 1:07 pm

You have to know how many $0.75 pads and how many $0.8 pads were sold. Hence both statements are insuffiecient.

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Stuart@KaplanGMAT: GMAT Instructor; Posts: 3225; Joined: Tue Jan 08, 2008 2:40 pmFollowed by: 614 members; Location: Toronto; Thanked: 1710 times; GMAT Score:800

Re: OG-10-129-> Explanation is weird

by Stuart@KaplanGMAT » Tue Jun 30, 2009 1:38 pm

ash_maverick wrote:At the beginning of the last month, a stationary store had in stocks 250 writing pads, which had cost the store $0.75 each.During the same month the store made only one purchase of writing pads . What was the total amount spent by the store on the writing pads it had in stock at the end of last months.

1-Last month the store purchased 150 writing pad for $.80 each.

2- Last week the total revenue from the sale of writing pad was $180.

Now, here is the problem i am facing. The Answer says E, but my answer is A.

I found the explanation in 10 OG really weird. See, i have to find the total amount spent on the pad. so i just have to add the amount spent on buying 250 @.75 and 150 @.80. This simply gives me the total amount spent. Now, form where on the earth the other amount comes into picture, the way it has been explained in 10 OG.

can somebody please explain me?

We need to determine exactly what the question is before we can possibly hope to answer it.

"What was the total amount spent by the store on the writing pads it had in stock at the end of last month?"

"end" is the most important word for this particular question.

You're 100% correct that (1) gives us enough information to calculate how much money the store spent on pads before last month and during last month. However, in order to answer the question posed, we also need to know how many pads were sold during the month.

For example, if the store sold 0 pads, then our answer would simply be:

250 * .75 + 150 * .80

However, if the store sold 400 pads last month, then our answer would be 0, since there were no pads left in stock.

(2) doesn't help us out very much. It only gives us the revenue from the last week; we have no idea what the revenue was for the rest of the month. Further, since we don't know the price per unit, we can't equate revenue with number sold.

Accordingly, we don't have enough info to answer the question: choose (E).

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

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aj5105: Legendary Member; Posts: 1169; Joined: Sun Jul 06, 2008 2:34 amFollowed by: 1 member; Thanked: 25 times

Re: OG-10-129-> Explanation is weird

by aj5105 » Tue Jun 30, 2009 7:39 pm

Thanks Stuart.

Stuart Kovinsky wrote:
ash_maverick wrote:At the beginning of the last month, a stationary store had in stocks 250 writing pads, which had cost the store $0.75 each.During the same month the store made only one purchase of writing pads . What was the total amount spent by the store on the writing pads it had in stock at the end of last months.

1-Last month the store purchased 150 writing pad for $.80 each.

2- Last week the total revenue from the sale of writing pad was $180.

Now, here is the problem i am facing. The Answer says E, but my answer is A.

I found the explanation in 10 OG really weird. See, i have to find the total amount spent on the pad. so i just have to add the amount spent on buying 250 @.75 and 150 @.80. This simply gives me the total amount spent. Now, form where on the earth the other amount comes into picture, the way it has been explained in 10 OG.

can somebody please explain me?
We need to determine exactly what the question is before we can possibly hope to answer it.

"What was the total amount spent by the store on the writing pads it had in stock at the end of last month?"

"end" is the most important word for this particular question.

You're 100% correct that (1) gives us enough information to calculate how much money the store spent on pads before last month and during last month. However, in order to answer the question posed, we also need to know how many pads were sold during the month.

For example, if the store sold 0 pads, then our answer would simply be:

250 * .75 + 150 * .80

However, if the store sold 400 pads last month, then our answer would be 0, since there were no pads left in stock.

(2) doesn't help us out very much. It only gives us the revenue from the last week; we have no idea what the revenue was for the rest of the month. Further, since we don't know the price per unit, we can't equate revenue with number sold.

Accordingly, we don't have enough info to answer the question: choose (E).

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ash_maverick: Senior | Next Rank: 100 Posts; Posts: 31; Joined: Sun Jan 07, 2007 11:13 pm

Re: OG-10-129-> Explanation is weird

by ash_maverick » Tue Jun 30, 2009 10:36 pm

Stuart Kovinsky wrote:
ash_maverick wrote:At the beginning of the last month, a stationary store had in stocks 250 writing pads, which had cost the store $0.75 each.During the same month the store made only one purchase of writing pads . What was the total amount spent by the store on the writing pads it had in stock at the end of last months.

1-Last month the store purchased 150 writing pad for $.80 each.

2- Last week the total revenue from the sale of writing pad was $180.

Now, here is the problem i am facing. The Answer says E, but my answer is A.

I found the explanation in 10 OG really weird. See, i have to find the total amount spent on the pad. so i just have to add the amount spent on buying 250 @.75 and 150 @.80. This simply gives me the total amount spent. Now, form where on the earth the other amount comes into picture, the way it has been explained in 10 OG.

can somebody please explain me?
We need to determine exactly what the question is before we can possibly hope to answer it.

"What was the total amount spent by the store on the writing pads it had in stock at the end of last month?"

"end" is the most important word for this particular question.

You're 100% correct that (1) gives us enough information to calculate how much money the store spent on pads before last month and during last month. However, in order to answer the question posed, we also need to know how many pads were sold during the month.

For example, if the store sold 0 pads, then our answer would simply be:

250 * .75 + 150 * .80

However, if the store sold 400 pads last month, then our answer would be 0, since there were no pads left in stock.

(2) doesn't help us out very much. It only gives us the revenue from the last week; we have no idea what the revenue was for the rest of the month. Further, since we don't know the price per unit, we can't equate revenue with number sold.

Accordingly, we don't have enough info to answer the question: choose (E).

Thanks Stuart....now it make sense to me.. thanks everybody for the discussion.

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