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A bookman purchased 30 copies of a new book released recently, 10 of
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17 Feb 2011, 15:11
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A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold? (A) 4 (B) 6 (C) 8 (D) 10 (E) 12
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Re: A bookman purchased 30 copies of a new book released recently, 10 of
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17 Feb 2011, 16:21
banksy wrote: 193. A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold? (A) 4 (B) 6 (C) 8 (D) 10 (E) 12 The bookman had 10 hardback ad 3010=20 paperback copies; 12 copies were sold, hence 3012=18 copies were left. Let # of paperback copies left be p then 15p+20(18p)=280 > p=16 > # of paperback copies sold is 2016=4. Answer: A.
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Re: A bookman purchased 30 copies of a new book released recently, 10 of
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21 Oct 2018, 04:14
banksy wrote: A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold?
(A) 4 (B) 6 (C) 8 (D) 10 (E) 12 Since 10 of the 30 books are hardback, the remaining 20 books are paperback. Since 12 of the 30 books are sold, the total number of unsold books = 3012 = 18. We can PLUG IN THE ANSWERS, which represent the number of paperback books that are sold. When the correct answer is plugged in, the total value of the unsold books = 280. B: 6 Since 6 of the 20 paperback books are sold, the number of unsold paperback books = 206 = 14. Since the total number of unsold books = 18, the number of unsold hardback books = 1814 = 4. Since the 14 unsold paperback books are priced at $20 each, while the 4 unsold hardback books are priced at $15 each, the total value of unsold books = (14*20) + (4*15) = 280 + 60 = 340. The total value of the unsold books is TOO HIGH. To reduce the total value of the unsold books, the less expensive type of book  paperback  must constitute a greater proportion of the unsold books. Implication: Fewer paperback books must be sold, so that a greater number of paperback books remain UNSOLD.
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Re: A bookman purchased 30 copies of a new book released recently, 10 of
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21 Oct 2018, 05:35
GMATGuruNY wrote: banksy wrote: A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold?
(A) 4 (B) 6 (C) 8 (D) 10 (E) 12 Since 10 of the 30 books are hardback, the remaining 20 books are paperback. Since 12 of the 30 books are sold, the total number of unsold books = 3012 = 18. We can PLUG IN THE ANSWERS, which represent the number of paperback books that are sold. When the correct answer is plugged in, the total value of the unsold books = 280. B: 6 Since 6 of the 20 paperback books are sold, the number of unsold paperback books = 206 = 14. Since the total number of unsold books = 18, the number of unsold hardback books = 1814 = 4. Since the 14 unsold paperback books are priced at $20 each, while the 4 unsold hardback books are priced at $15 each, the total value of unsold books = (14*20) + (4*15) = 280 + 60 = 340. The total value of the unsold books is TOO HIGH. To reduce the total value of the unsold books, the less expensive type of book  paperback  must constitute a greater proportion of the unsold books. Implication: Fewer paperback books must be sold, so that a greater number of paperback books remain UNSOLD. Nice Approach.However I had a query. When I read the question stem for the first time. A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold? I was confused if already 10 are hard back a nd sold $20 and remaining are paperpack and sold
for $15..Why does it again reiterate If 12 copies were sold... Can you please help me understand the way it i constructed?



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A bookman purchased 30 copies of a new book released recently, 10 of
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21 Oct 2018, 06:40
banksy wrote: A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold?
(A) 4 (B) 6 (C) 8 (D) 10 (E) 12 Now let us look at different ways to do this question(I) Weighted averageIf you know this, I would surely recommend thistotal books unsold = \(3012=18\) cost of these 18 books is 280.. Had all these been H 20 per book, cost would be 18*20=360 And Had all these been P @ 15 per book, cost would be 18*15=270 so Number of books of P = \(18*\frac{360280}{360270}=18*\frac{8}{9}=16\) so 16 out of 20 paperback are unsold and remaining 4 are sold (II) SubstitutionIf you are stuck, I would recommend thislet us take choice A  4.. so 4 out of 20 paperback are sold, and remaining 16 are unsold, costing \(16*15=240\)\(\) Total unsold is 18, so 1816 or 2 are hardback, costing 2*20=40 total cost of unsold, thus, is \(240+40=280\) and given is also 280 so choice A is correct (III) Algebraicthere can be two equations... \(H+P=12.......H=12P\)...(i) \(20*(10H)+15*(20P)=280..........20020H+30015P=280..........20H+15P=220\) substitute value of H in it \(20(12P)+15P=220.........24020P+15P=220.........5P=20....P=4\) A
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Re: A bookman purchased 30 copies of a new book released recently, 10 of
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21 Oct 2018, 07:23
chetan2u wrote: banksy wrote: A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold?
(A) 4 (B) 6 (C) 8 (D) 10 (E) 12 Now let us look at different ways to do this question(I) Weighted averageIf you know this, I would surely recommend thistotal books unsold = \(3012=18\) cost of these 18 books is 280.. Had all these been H 20 per book, cost would be 18*20=360 And Had all these been P 20 per book, cost would be 18*15=270 so Number of books of P = \(18*\frac{360280}{360270}=18*\frac{8}{9}=16\) so 16 out of 20 paperback are unsold and remaining 4 are sold (II) SubstitutionIf you are stuck, I would recommend thislet us take choice A  4.. so 4 out of 20 paperback are sold, and remaining 16 are unsold, costing \(16*15=240\)\(\) Total unsold is 18, so 1816 or 2 are hardback, costing 2*20=40 total cost of unsold, thus, is \(240+40=280\) and given is also 280 so choice A is correct (III) Algebraicthere can be two equations... \(H+P=12.......H=12P\)...(i) \(20*(10H)+15*(20P)=280..........20020H+30015P=280..........20H+15P=220\) substitute value of H in it \(20(12P)+15P=220.........24020P+15P=220.........5P=20....P=4\) A Chetan sir .Can you please help me with this When I read the question stem for the first time. A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold? I was confused if already 10 are hard back and sold $20 and remaining are paperpack and sold for $15..Why does it again reiterate If 12 copies were sold... Can you please help me understand the way it i constructed?



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Re: A bookman purchased 30 copies of a new book released recently, 10 of
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21 Oct 2018, 07:29
prabsahi wrote: chetan2u wrote: banksy wrote: A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold?
(A) 4 (B) 6 (C) 8 (D) 10 (E) 12 Now let us look at different ways to do this question(I) Weighted averageIf you know this, I would surely recommend thistotal books unsold = \(3012=18\) cost of these 18 books is 280.. Had all these been H 20 per book, cost would be 18*20=360 And Had all these been P 20 per book, cost would be 18*15=270 so Number of books of P = \(18*\frac{360280}{360270}=18*\frac{8}{9}=16\) so 16 out of 20 paperback are unsold and remaining 4 are sold (II) SubstitutionIf you are stuck, I would recommend thislet us take choice A  4.. so 4 out of 20 paperback are sold, and remaining 16 are unsold, costing \(16*15=240\)\(\) Total unsold is 18, so 1816 or 2 are hardback, costing 2*20=40 total cost of unsold, thus, is \(240+40=280\) and given is also 280 so choice A is correct (III) Algebraicthere can be two equations... \(H+P=12.......H=12P\)...(i) \(20*(10H)+15*(20P)=280..........20020H+30015P=280..........20H+15P=220\) substitute value of H in it \(20(12P)+15P=220.........24020P+15P=220.........5P=20....P=4\) A Chetan sir .Can you please help me with this When I read the question stem for the first time. A bookman purchased 30 copies of a new book released recently, 10 of which are hardback and sold for $20 each, and rest are paperback and sold for $15 each. If 12 copies were sold and the total value of the remaining books was 280, how many paperback copies were sold? I was confused if already 10 are hard back and sold $20 and remaining are paperpack and sold for $15..Why does it again reiterate If 12 copies were sold... Can you please help me understand the way it i constructed? Hi.. The give away is the verb ARE.. These are sold for 50$ would mean these are priced at 50$.. Had it been these were sold for 50$, yes it would mean they have already been sold... .
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Re: A bookman purchased 30 copies of a new book released recently, 10 of
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21 Oct 2018, 07:33
Hi.. The give away is the verb ARE.. These are sold for 50$ would mean these are priced at 50$.. Had it been these were sold for 50$, yes it would mean they have already been sold...
.[/quote]
So its more like Jeans are sold for $20.(MEANS its priced at $20)
Thank you so much.Just wanted to make sure I don't have the same GAP for new problems of this type.




Re: A bookman purchased 30 copies of a new book released recently, 10 of
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