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a, b, and c are integers and a < b < c. S is the set of all

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a, b, and c are integers and a < b < c. S is the set of all [#permalink] New post 27 Oct 2009, 22:18
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a, b, and c are integers and a < b < c. S is the set of all integers from a to b, inclusive. Q is the set of all integers from b to c, inclusive. The median of set S is (3/4)b. The median of set Q is (7/8)c. If R is the set of all integers from a to c, inclusive, what fraction of c is the median of set R?

(A) 3/8
(B) 1/2
(C) 11/16
(D) 5/7
(E) 3/4

\sqrt{I solved it lke this...
for set S (a+b)/ 2 = (3/4 ) B
for set Q (b+c)/2 = (7c)/8
after solving we got
3c = 4b = 8a
median for set R is b so
4b = 3c
b = (3c)/4..

got E ..plasde tell me am i wrong somewhere?
Rohit}
[Reveal] Spoiler: OA

Last edited by Bunuel on 20 Aug 2012, 00:50, edited 1 time in total.
Edited the question and added the OA.
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Re: Statistics.. [#permalink] New post 27 Oct 2009, 22:39
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KocharRohit wrote:
a, b, and c are integers and a < b < c. S is the set of all integers from a to b, inclusive. Q is the set of all integers from b to c, inclusive. The median of set S is (3/4)b. The median of set Q is (7/8)c. If R is the set of all integers from a to c, inclusive, what fraction of c is the median of set R?
(A) 3/8
(B) 1/2
(C) 11/16
(D) 5/7
(E) 3/4

I solved it lke this...
for set S (a+b)/ 2 = (3/4 ) B
for set Q (b+c)/2 = (7c)/8
after solving we got
3c = 4b = 8a
median for set R is b so
4b = 3c
b = (3c)/4..

got E ..plasde tell me am i wrong somewhere?
Rohit


Given:
Median of S=\frac{a+b}{2}=b*\frac{3}{4} --> b=2a;

Median of Q=\frac{b+c}{2}=c*\frac{7}{8} --> b=c*\frac{3}{4} --> 2a=c*\frac{3}{4} --> a=c*\frac{3}{8};

Median of R=\frac{a+c}{2}=\frac{c*\frac{3}{8}+c}{2}=c*\frac{11}{16}

Answer: C (\frac{11}{16})
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Re: Statistics.. [#permalink] New post 27 Oct 2009, 22:46
Set R has three numbers..a , b , c..so why did we take median as
(a+c)/2 shudnt it be only b??
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Re: Statistics.. [#permalink] New post 27 Oct 2009, 22:59
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KocharRohit wrote:
Set R has three numbers..a , b , c..so why did we take median as
(a+c)/2 shudnt it be only b??


Not so. We are told that a<b<c, but not that they are consecutive integers, it could be 3<55<79. So set R in that case would be all integers from 3 to 79 inclusive. And b not necessarily would be the median. Median would be (3+79)/2=41.

Hope it's clear.
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Re: Statistics.. [#permalink] New post 27 Oct 2009, 23:01
Thanks Buddy..much clear now..
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Re: Statistics.. [#permalink] New post 28 Oct 2009, 16:27
got the same C

Though, i am afraid, how i will manage it under stress, and under time constraints
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Median advanced and tricky [#permalink] New post 12 Jan 2010, 03:31
a, b, and c are integers and a < b < c. S is the set of all integers from a to b, inclusive. Q is the set of all integers from b to c, inclusive. The median of set S is (3/4)b. The median of set Q is (7/8)c. If R is the set of all integers from a to c, inclusive, what fraction of c is the median of set R?

(A) 3/8
(B) 1/2
(C) 11/16
(D) 5/7
(E) 3/4
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Re: Median advanced and tricky [#permalink] New post 12 Jan 2010, 04:21
chetan2u wrote:
C..


Why :?:
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Re: Median advanced and tricky [#permalink] New post 12 Jan 2010, 04:46
shalva wrote:
chetan2u wrote:
C..


Why :?:

for nos between b and c ,7c/8 is the median..means c has to be a multiple of 4 or 8... but for 3b/4 to be a median, c has to be a multiple of 8 .....
lets take it as 8.. median=7*8/7=7.... set is 6,7,8...this makes b=6...median=6*3/4= 9/2.... so the set is 3,4,5,6..
set Q is 3,4,5,6,7,8.. the median is 11/2,which is 11/16 of 8 or c.... we can try the same with other multiple of 8 also..
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Re: Median advanced and tricky [#permalink] New post 16 Jan 2010, 11:54
i fails to understand how can the median between two number a and b can be
a+b/2.It depends on number of integer between the range so median between
1 6 and 7 cannot be 4 it will be 6 .so please calcify the approach in details
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Re: Median advanced and tricky [#permalink] New post 16 Jan 2010, 12:43
arghya05 wrote:
i fails to understand how can the median between two number a and b can be
a+b/2.It depends on number of integer between the range so median between
1 6 and 7 cannot be 4 it will be 6 .so please calcify the approach in details


Well, from some point you are right: median divides the sample in two parts: Equal number of observations in each. It doesn't necessarily mean (a+b)/2

But you should also consider that, in set S, there are "all integers from a to b, inclusive", and in set Q there are "all integers from b to c, inclusive"

So these sets are sets of consecutive integers. In this case Mean=Median=(a+b)/2
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Re: a, b, and c are integers and a < b < c. S is the set of all [#permalink] New post 23 Feb 2014, 02:51
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Re: a, b, and c are integers and a < b < c. S is the set of all   [#permalink] 23 Feb 2014, 02:51
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