A certain packing

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A certain packing

by BTGmoderatorDC » Thu Feb 01, 2018 5:30 pm
A certain packing box contains books between 50 to 60. How many books exactly does that box contains?

(1) If the books are counted by three, there will be one book left over.

(2) If the books are counted by six, there will be one book left over.

Why statement 1 isn't sufficient?

OA B
Source: — Data Sufficiency |

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by GMATGuruNY » Fri Feb 02, 2018 3:28 am
lheiannie07 wrote:A certain packing box contains books between 50 to 60. How many books exactly does that box contains?

(1) If the books are counted by three, there will be one book left over.

(2) If the books are counted by six, there will be one book left over.
Statement 1:
In other words, the total number of books is ONE MORE THAN A MULTIPLE OF 3.
Multiples of 3 between 50 and 60, inclusive:
51, 54, 57, 60.
Adding 1 to each of these options, we get:
52, 55, 58, 61.
Since the option in red is not between 50 and 60, the total number of books could be 52, 55, or 58.
INSUFFICIENT.

Statement 2:
In other words, the total number of books is ONE MORE THAN A MULTIPLE OF 6.
Multiples of 6 between 50 and 60, inclusive:
54, 60.
If we add 1 to each of these options, we get:
55, 61.
Since the option in red is not between 50 and 60, the total number of books = 55.
SUFFICIENT.

The correct answer is B.
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by Scott@TargetTestPrep » Mon Feb 05, 2018 9:41 am
lheiannie07 wrote:A certain packing box contains books between 50 to 60. How many books exactly does that box contains?

(1) If the books are counted by three, there will be one book left over.

(2) If the books are counted by six, there will be one book left over.
We are given that there are between 50 and 60 books in a box. We need to determine how many books are in the box.

Statement One Alone:

If the books are counted by three, there will be one book left over.

From statement one, we see that if the number of books is divided by 3, there will be a remainder of 1. In other words, the number of books is 1 more more than a multiple of 3. Thus, the possible number of books is 52, 55, or 58. Statement one alone is not sufficient to answer the question.

Statement Two Alone:

If the books are counted by six, there will be one book left over.

From statement two, we see that if the number of books is divided by 6, there will be a remainder of 1. In other words, the number of books is 1 more than a multiple of 6. So the only possible number of books is 55. Statement two alone is sufficient to answer the question.

Answer:B

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