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really hard question

by bupbebeo » Tue May 11, 2010 11:37 pm
at a certain department store present-wrapping counter. Each clerk will wrap no fewer than 20 and no more than 30 presents per hour. If 70 people are standing in line, will all of their presents be wrapped after 1 hour.

1. Each person in line has at least 1 present to be wrapped by one of the six clerks at the counter


2. If each clerk in line had one more present to be wrapped. 9 clerks would be required to guarantee that every present would be wrapped in 1 hour.
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by kstv » Tue May 11, 2010 11:48 pm
2) to guarantee that each clerk will complete in 1 hour, the number of gifts should be the minimum i.e. 20 gifts to be wrapped by each. 9 clerks wrap 20 gifts = 180 gifts in total. But actual no of clerks in not known. Insuff

1) Each person in line has alteast one gift but total no of gifts cannot be ascertained. Insuff

Combining 1 and 2 we know there are 180 gifts and 6 clerks i.e 30 gifts have to be wrapped by each. 30 is the maximum that can be wrapped by each clerk. So it is possible in one hour.

IMO C.
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by iamseer » Wed May 12, 2010 12:04 am
In 1 hour, min 20 gifts and max 30 gifts can be wrapped by one clerk.
To find if all presents of the 70 people would be wrapped we need to find the total number of presents and total number of clerks.

ABCDE
from 1:
each person has at least 1.... so number of presents per person in queue could be 1... could be 100....
Number of clerks =6
So, Not Sufficient

BCE
from 2:
if one present more per clerk, 9 clerks required to guarantee. therefore NEW number of presents = 9*20=180. Therefore original number of presents = 180-9=171

We still don't know, how many clerks are there for sure.
So, Not Sufficient

CE
Combining 1 and 2:
Number of clerks:6
Number pf presents: 70*(summation of 70 numbers >=1) = 171

Now 6 clerks can wrap a minimum of 120 and maximum of 180. B'cos 120<171<180, all presents could be wrapped or not be wrapped depending upon how many presents each clerk wraps.

Not Sufficient

IMO answer E

If number was less than 120.... a definite Yes was possible
If number was greater than 180... a definite NO was possible
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by amer siddiqui » Wed May 12, 2010 12:40 am
From (1) we know that there are 6 clerks so the min no. presents that can be wrapped is 120 (6 * 20) and the max is 180 (6*30). However this statement says that each of the 70 customers have at least one present so we do not know whether the total presents fall within this range of 120-180. Therefore, INSUFFICIENT

From (2) we know that if each customer had one more present and there were 9 clerks then their wrapping could be guaranteed. Let us assume that the actual total is T. Now give each customer one more present. The new total is T+70. The max that 9 clerks can wrap is 9*30= 270. Since T+70 is a guaranteed number, T+70 is less than or equal to 270. This means that T is less than or equal to 200. However, we still don't know the number of clerks. INSUFFICIENT

If we combine (1) and (2), we know that there are between 70 and 200 presents. We also know that there are 6 clerks. 6 Clerks can wrap a max of 180 presents. If there are less than 180 presents, then all can be wrapped but if there are more than 180, then some may remain unwrapped. INSUFFICIENT

ANSWER E
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by bupbebeo » Wed May 12, 2010 12:53 am
kstv wrote:2) to guarantee that each clerk will complete in 1 hour, the number of gifts should be the minimum i.e. 20 gifts to be wrapped by each. 9 clerks wrap 20 gifts = 180 gifts in total. But actual no of clerks in not known. Insuff

1) Each person in line has alteast one gift but total no of gifts cannot be ascertained. Insuff

Combining 1 and 2 we know there are 180 gifts and 6 clerks i.e 30 gifts have to be wrapped by each. 30 is the maximum that can be wrapped by each clerk. So it is possible in one hour.

IMO C.
180 is just assumed number. why you have 180 not 270 or other numbers?
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by ballubalraj » Wed May 12, 2010 12:56 am
2. If each clerk in line had one more present to be wrapped. 9 clerks would be required to guarantee that every present would be wrapped in 1 hour.
[\Unquote]

The second statement is not clear - looks like something is wrong in the wordings. Did each customer in line had one more present or did each clerk had one present left unwrapped?
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by bupbebeo » Wed May 12, 2010 12:58 am
iamseer wrote:In 1 hour, min 20 gifts and max 30 gifts can be wrapped by one clerk.
To find if all presents of the 70 people would be wrapped we need to find the total number of presents and total number of clerks.

ABCDE
from 1:
each person has at least 1.... so number of presents per person in queue could be 1... could be 100....
Number of clerks =6
So, Not Sufficient

BCE
from 2:
if one present more per clerk, 9 clerks required to guarantee. therefore NEW number of presents = 9*20=180. Therefore original number of presents = 180-9=171

We still don't know, how many clerks are there for sure.
So, Not Sufficient

CE
Combining 1 and 2:
Number of clerks:6
Number pf presents: 70*(summation of 70 numbers >=1) = 171

Now 6 clerks can wrap a minimum of 120 and maximum of 180. B'cos 120<171<180, all presents could be wrapped or not be wrapped depending upon how many presents each clerk wraps.

Not Sufficient

IMO answer E

If number was less than 120.... a definite Yes was possible
If number was greater than 180... a definite NO was possible

Hi iamseer, you might misunderstand the question. In the second statement, it says each person has one more present not clerk has one more present to wrap. Be careful.
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by amer siddiqui » Wed May 12, 2010 12:59 am
bupbebeo - what's the answer and where did you see this q?
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by bupbebeo » Wed May 12, 2010 1:20 am
amer siddiqui wrote:bupbebeo - what's the answer and where did you see this q?
OA is C. it appears in Kaplan CAT test
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by amer siddiqui » Wed May 12, 2010 1:28 am
I see, thanks! IS it possible to set out the explanation from Kaplan as to how the two statements together are sufficient?
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by bupbebeo » Wed May 12, 2010 2:05 am
amer siddiqui wrote:I see, thanks! IS it possible to set out the explanation from Kaplan as to how the two statements together are sufficient?
the explanation in the test is so vague. that's why I post the question on the forum for everyone to discuss.
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by kstv » Wed May 12, 2010 2:50 am
If it is not too tedious to post the OE, it will help to evaluate whether the reasoning was correct.
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by outreach » Wed May 12, 2010 3:01 am
Stuart has answered this problem
https://www.beatthegmat.com/department-store-t56606.html
bupbebeo wrote:at a certain department store present-wrapping counter. Each clerk will wrap no fewer than 20 and no more than 30 presents per hour. If 70 people are standing in line, will all of their presents be wrapped after 1 hour.

1. Each person in line has at least 1 present to be wrapped by one of the six clerks at the counter


2. If each clerk in line had one more present to be wrapped. 9 clerks would be required to guarantee that every present would be wrapped in 1 hour.
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by iamseer » Wed May 12, 2010 4:36 am
This is the first post:
bupbebeo wrote:at a certain department store present-wrapping counter. Each clerk will wrap no fewer than 20 and no more than 30 presents per hour. If 70 people are standing in line, will all of their presents be wrapped after 1 hour.

1. Each person in line has at least 1 present to be wrapped by one of the six clerks at the counter


2. If each clerk in line had one more present to be wrapped. 9 clerks would be required to guarantee that every present would be wrapped in 1 hour.
Please be careful in typing the question stem next time.

change of one word "person" to "clerk" changes answer from C to E.... changes the number of presents from 110 to 171.
"Choose to chance the rapids and dance the tides"
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by iamseer » Wed May 12, 2010 4:39 am
New explanation for the correct question stem:

In 1 hour, min 20 gifts and max 30 gifts can be wrapped by one clerk.
To find if all presents of the 70 people would be wrapped we need to find the total number of presents and total number of clerks.

ABCDE
from 1:
each person has at least 1.... so number of presents per person in queue could be 1... could be 100....
Number of clerks =6
So, Not Sufficient

BCE
from 2:
if one present more per person, 9 clerks required to guarantee. therefore NEW number of presents = 9*20=180. Therefore original number of presents = 180-70=110

We still don't know, how many clerks are there for sure.
So, Not Sufficient

CE
Combining 1 and 2:
Number of clerks:6
Number pf presents: 110

Now 6 clerks can wrap a minimum of 120. So they will definitely wrap 110.
IMO answer C
"Choose to chance the rapids and dance the tides"
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