avg of m integers

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gmatv09: Master | Next Rank: 500 Posts; Posts: 256; Joined: Mon Aug 10, 2009 6:31 pm; Thanked: 3 times

by gmatv09 » Mon Nov 09, 2009 10:53 pm

If m is a positive odd integer, what is the avg of a certain set of m integers?

(1) The integers in the set are consecutive multiples of 3

(2) The median of the set of integers is 33

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Source: Beat The GMAT — Data Sufficiency | Mon Nov 09, 2009 10:53 pm

heshamelaziry: Legendary Member; Posts: 869; Joined: Wed Aug 26, 2009 3:49 pmFollowed by: 3 members; Location: California; Thanked: 13 times

by heshamelaziry » Mon Nov 09, 2009 11:25 pm

IMO E.

if the set has 3,6 the average is 3. if the set has 3,6,9 the average is 6. Stetmnt 1 ---> insuficient.

when 33 is the median, many multiples of 3 above and below 33 could be sufficient and the average will differ; range unknown. ----> insufficient.

Combo:

No new info can be deduced.

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okigbo: Master | Next Rank: 500 Posts; Posts: 177; Joined: Sun Aug 02, 2009 9:39 pm; Thanked: 6 times

by okigbo » Mon Nov 09, 2009 11:33 pm

IMO the answer is C

For a consecutive set of integers, median=mean. You need both statements.

Let me know if I am wrong.

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heshamelaziry: Legendary Member; Posts: 869; Joined: Wed Aug 26, 2009 3:49 pmFollowed by: 3 members; Location: California; Thanked: 13 times

by heshamelaziry » Mon Nov 09, 2009 11:46 pm

You are absoulutly correct. I am sufferering from memory loss

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vivekjaiswal: Master | Next Rank: 500 Posts; Posts: 107; Joined: Tue Sep 15, 2009 7:18 pm; Location: Pune, India; Thanked: 6 times; GMAT Score:630

by vivekjaiswal » Tue Nov 10, 2009 12:45 am

okigbo wrote:IMO the answer is C

For a consecutive set of integers, median=mean. You need both statements.

Let me know if I am wrong.

Even i think its C...
Thanks for reminding this important relationship between mean and median of an equally spaced set.

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xcusemeplz2009: Master | Next Rank: 500 Posts; Posts: 399; Joined: Wed Apr 15, 2009 3:48 am; Location: india; Thanked: 39 times

by xcusemeplz2009 » Tue Nov 10, 2009 1:02 am

IMO C

M CAN BE ANYTHING 1,3,5,7

STATEMNET1) M CAN BE 3 6 9 OR 3 6 9 12 15 ......
HENCE AVG IS NOT CONISITENT

STATMENT2) M CAN BE 32 33 34 OR
1 33 100

AVG ARE DIFF..

COMB...
M CAN BE 27 30 33 36 39
OR 30 33 36

LET ANY NO CASES
MED AND MEAN IS SAME 33

HENCE C

It does not matter how many times you get knocked down , but how many times you get up

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