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# During a 10-week summer vacation, was the average

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Joined: 04 Sep 2008
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During a 10-week summer vacation, was the average [#permalink]

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27 Oct 2008, 06:02
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During a 10-week summer vacation, was the average (arithmetic mean) number of books that Carolyn read per week greater than the average number of books that Jacob read per week?
(1) Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.
(2) During the last 5 weeks of the vacation, Carolyn read a total of 3 books more than Jacob.

Pls explain
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rampuria

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27 Oct 2008, 09:11
[quote="rampuria"]During a 10-week summer vacation, was the average (arithmetic mean) number of books that Carolyn read per week greater than the average number of books that Jacob read per week?
(1) Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.
(2) During the last 5 weeks of the vacation, Carolyn read a total of 3 books more than Jacob.

from 1
x ,y number of books
x/10*2 = x/5 > y/5-5

x > y-25 ie, x/10-y/10> -25/10>-2.5 thus sure y/10 - x/10<2.5 ( x, y cant be -ve as it is a number of books)

..........suff

from2

during the first 5 weeks

total books by carol = x+y+3, total books Jackop = z+y+3

as long as x,z are unknown......insuff

A

Last edited by yezz on 28 Oct 2008, 01:11, edited 3 times in total.
VP
Joined: 30 Jun 2008
Posts: 1022

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27 Oct 2008, 19:15
rampuria wrote:
During a 10-week summer vacation, was the average (arithmetic mean) number of books that Carolyn read per week greater than the average number of books that Jacob read per week?
(1) Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.
(2) During the last 5 weeks of the vacation, Carolyn read a total of 3 books more than Jacob.

Pls explain

c = avg books read by carolyn
j = avg books read by jacob

question --> c>j ?

(1) 2c = 2j-5 -------> implies c > j .... suff.
(2) we have no info about first 5 weeks. Maybe jacob read more books than carolyn read ?? No idea .... not suff ...

A
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Joined: 03 Mar 2008
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27 Oct 2008, 22:51
amitdgr wrote:
rampuria wrote:
During a 10-week summer vacation, was the average (arithmetic mean) number of books that Carolyn read per week greater than the average number of books that Jacob read per week?
(1) Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.
(2) During the last 5 weeks of the vacation, Carolyn read a total of 3 books more than Jacob.

Pls explain

c = avg books read by carolyn
j = avg books read by jacob

question --> c>j ?

(1) 2c = 2j-5 -------> implies c > j .... suff.
(2) we have no info about first 5 weeks. Maybe jacob read more books than carolyn read ?? No idea .... not suff ...

A

Statement A says 2c > 2j -5
This does not imply c > j....what if c = 2 and j = 3 ?
If it were 2c = 2j - 5 and both c and j > 0 then it were a different story
Statement A is insufficient

Statement B is also insufficient
Together does not help much either

IMO E
OA pls
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Joined: 03 Mar 2008
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27 Oct 2008, 22:54
yezz wrote:
rampuria wrote:
During a 10-week summer vacation, was the average (arithmetic mean) number of books that Carolyn read per week greater than the average number of books that Jacob read per week?
(1) Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.
(2) During the last 5 weeks of the vacation, Carolyn read a total of 3 books more than Jacob.

from 1
x ,y number of books
x/10*2 = x/5 > y/5-5

x > y-25.
.........suff

from2

during the first 5 weeks

total books by carol = x+y+3, total books Jackop = z+y+3

as long as x,z are unknown......insuff

A

x > y - 25 is not sufficient to say that x > y
what if x = 25 and y = 27 ?
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28 Oct 2008, 00:49
ya it should be E. I made a very silly mistake
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Joined: 17 Jun 2008
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29 Oct 2008, 04:15
I think, it should be B. But, But, my approach may be wrong. I will wait for the OA.

Suppose, C and J are the weekly average number of books that C and J read.

Then, for five weeks, 5C = 5J + 3 and this clearly tells that C > J.

However, I somehow feel, I should not be multiplying the average by 5 as it could also be possible that in the first 5 weeks, many more books were read than in the second half or vice versa.
Re: DS   [#permalink] 29 Oct 2008, 04:15
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