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T contains 6

by sanju09 » Mon Apr 13, 2009 1:20 am
Set T contains 6 different prime numbers. Which of the following could be the median of set T?
A. 2
B. 0.3
C. 9.5
D. 26.8
E. 39
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by deagez » Mon Apr 13, 2009 1:49 am
Since there are six numbers you would have take the average of two consecutive prime numbers to get the median of any set.

I just kept listing primes until I got a number that was one of the answers.

37 and 41 yielded 39 (answer E)
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by scoobydooby » Mon Apr 13, 2009 1:50 am
would go for E

2 is the smallest and the only even prime. if we arranged the primes in increasing order, the median of the 6 numbers will be (3rd prime+4th prime)/2, or odd+odd/2 or even/2 which would leave an integer

so B, C and D are out as they are not integers.

cant be 2. as we cant add two different primes to make 4.

that leaves 39.
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by sanju09 » Mon Apr 13, 2009 2:07 am
deagez wrote:Since there are six numbers you would have take the average of two consecutive prime numbers to get the median of any set.

I just kept listing primes until I got a number that was one of the answers.

37 and 41 yielded 39 (answer E)
Your way, if not risky at this occasion, is a real time killing for sure; moreover it is never mentioned that we need to consider consecutive primes only. In problems that read to look for 'could be' choices, always come down to the concrete conclusion from the stem that which of the following may or may not be the general appearance of the right choice, see scoobydooby using the same trick here by striking out the unwanted choices that do not follow the thumb rule.:)

a question: Are there more prime pairs other than 37 and 41, which could average to 39?
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by dumb.doofus » Wed Apr 15, 2009 9:57 pm
sanju09 wrote:
deagez wrote:Since there are six numbers you would have take the average of two consecutive prime numbers to get the median of any set.

I just kept listing primes until I got a number that was one of the answers.

37 and 41 yielded 39 (answer E)
Your way, if not risky at this occasion, is a real time k!II!ng for sure; moreover it is never mentioned that we need to consider consecutive primes only. In problems that read to look for 'could be' choices, always come down to the concrete conclusion from the stem that which of the following may or may not be the general appearance of the right choice, see scoobydooby using the same trick here by striking out the unwanted choices that do not follow the thumb rule.:)

a question: Are there more prime pairs other than 37 and 41, which could average to 39?
Anything that adds up to 78 .. for now one ex comes to mind is 11, 67 :-)
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by 4seasoncentre » Wed Apr 15, 2009 10:07 pm
Rule out A and B because they are too low to be the median of 6 numbers.

For the others, I just ignored the fact that there were 6 numbers in the set.

Since we are looking for the median, we just have to take the remaining possible solutions and find the first prime number less than, and first prime number greater than.

So for 9.5 (7,11)
26.8 (23, 27)
39 (37,41)

Only 39 is the median of the prime numbers before and after it. And I am fairly confident there are at least two prime numbers before 37.
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by sanju09 » Thu Apr 16, 2009 2:54 am
Your answer doesn’t fit to your name, dumb.doofus! :D

Why do you feel 27 a prime, 4seasoncentre? :?

OA is E and scoobydooby did full justice in proving his point, but I am not trying to judge anybody here, please mind my seniorsB-)
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by 4seasoncentre » Thu Apr 16, 2009 6:47 am
sanju09 wrote:Your answer doesn’t fit to your name, dumb.doofus! :D

Why do you feel 27 a prime, 4seasoncentre? :?
oops :oops:

well in this case i would have gotten away with it
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by Mr2Bits » Thu Apr 16, 2009 6:52 am
sanju09 wrote:Your answer doesn’t fit to your name, dumb.doofus! :D

Why do you feel 27 a prime, 4seasoncentre? :?

OA is E and scoobydooby did full justice in proving his point, but I am not trying to judge anybody here, please mind my seniorsB-)
Here is my elucidation, you are just really a true a-hole in the way you speak to people? Do you enjoy this or do you just not recognize how demoralizing you are? Please do everyone a favor and go elsewhere so you don't bring hard-working people around here down.
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by vittalgmat » Thu Apr 16, 2009 4:54 pm
E could be the median.
coz without even calculating one can see why others cannot be the median.
I used some hackish crude logic...

A. 2 ----> smallest prime.. so cannot be median!!!.
B. 0.3 : No. prime # are +ve ONLY by definition. so we cannot have -ve # to make up the half lesser then the median.
C. 9.5 ---> if 9.5 is median, the middle 2 numbers are 9 and 10, both are not prime.
D. 26.8. ----> something.8 sounds fishy.
E. 39 --> looks real. Test it out. u will see indeed this is median.
if u choose 3 primes < 39 and 3 primes > 39.
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by bubbliiiiiiii » Fri Apr 17, 2009 1:57 am
vittalgmat wrote:E could be the median.
coz without even calculating one can see why others cannot be the median.
I used some hackish crude logic...

A. 2 ----> smallest prime.. so cannot be median!!!.
B. 0.3 : No. prime # are +ve ONLY by definition. so we cannot have -ve # to make up the half lesser then the median.
C. 9.5 ---> if 9.5 is median, the middle 2 numbers are 9 and 10, both are not prime.
D. 26.8. ----> something.8 sounds fishy.
E. 39 --> looks real. Test it out. u will see indeed this is median.
if u choose 3 primes < 39 and 3 primes > 39.


Hi All,

My method would be,

Since there are six prime numbers, the median has to be a mean of 2 mid terms.

Since all the numbers are prime, sum of any two primes must be even.

An even when divided by 2, again an even, would yield a integer as median, which rules out option B, C and D.

Considering, A and E, A cannot be the answer since a sum of 4 as a median cannot be obtained by addition of two prime numbers.

Thus, E is the answer.

Hope it sounds sensible.

:D
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