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C is the finite sequence \(C_1\)=0,\(C_2\)=\(\frac{1}{2}\),\(C_3\)=\(\frac{2}{3}\)...determined by the equation \(C_f\)=\(\frac{f-1}{f}\)where f is a positive integer.D is a similiar finite sequence determined by the equation \(D_g\) = \(\frac{g}{g+1}\) where g is a positive integer,Is the sum of allthe values in C equal to the sum of all the values in D?
1.g \(\neq\)f 2.The difference between the median of C and the median of D is \(\frac{3}{43}\)
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
B for me too. Let's look at the sets when sum of all the values of C is equal to that of D C: \(0\); \(\frac{1}{2}\); \(\frac{2}{3}\); \(\frac{3}{4}\);
D: \(\frac{1}{2}\); \(\frac{2}{3}\); \(\frac{3}{4}\); as we can see, f=g+1 that leads to the fact that median of C is less than median of D (as C has more members that D). Let's add one member to each set:
D: \(\frac{1}{2}\); \(\frac{2}{3}\); \(\frac{3}{4}\); \(\frac{4}{5}\); again, median of C is less than median of D, and it will continue as long as we increase number of members in both sets. So, if sum of all values of C is equal to that of D, then the difference between the median of C and the median of D is negative. Hence, B is sufficient.
Originally posted by mnpqxyzt on 07 Sep 2009, 16:52.
Last edited by mnpqxyzt on 08 Sep 2009, 08:40, edited 1 time in total.
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1) Insufficient ( f-1)/f = 1 - 1/f, hence sum of C = f - (1 + 1/2 + 1/3 + ... + 1/f) = (f-1) + (1/2 + 1/3 + .... + 1/f) g/(g+1) = 1- 1/(g+1), hence sum of D = g - (1/2 + 1/3 + ... + 1/g+1)
So sum of C = sum of G if and only if f-1 = g
2) median of C is 1/c or (1/c1 + 1/c2) /2 median of D is 1/d or (1/d1 + 1/d2) /2
We may have 1/c - 1/d = 3/43 or (1/c1 + 1/c2) /2 - ((1/d1 + 1/d2) /2) = 3/43 or 1/c - ((1/d1 + 1/d2) /2) = 3/43 or (1/c1 + 1/c2) /2 - 1/d = 3/43 we can not find c and d with only one equation like that so insufficient
1.) This is insufficient,,we can prove by taking f = 3 ; g = 4 and f = 4 ; g = 3
2.) now, the condition arises; Case1: f is odd, g is odd Case2: f is even ,g is odd Case3: f is odd , g is even Case4: f is even, g is even
I tried to use al these cases, but did not get much luck, got stuck when either f or g is even
For Case1: i m getting, f -g = 46/43. (but we need f = g +1 for their sum to be equal) => their sum is not equal.. But, i am not sure, how to solve for other three cases..
PS:- I don't want to solve only one question on GDAY, so, i will pick either B or E in this case..and that will be a wild guess..
C is the finite sequence \(C_1\)=0,\(C_2\)=\(\frac{1}{2}\),\(C_3\)=\(\frac{2}{3}\)...determined by the equation \(C_f\)=\(\frac{f-1}{f}\)where f is a positive integer. D is a similiar finite sequence determined by the equation \(D_g\) = \(\frac{g}{g+1}\) where g is a positive integer, Is the sum of allthe values in C equal to the sum of all the values in D?
1.g \(\neq\)f 2.The difference between the median of C and the median of D is \(\frac{3}{43}\)
Phew this took a while to type!Anybody with a detailed explanation?
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What is the source of the question? The question looks incorrrect to me because the difference (\(\frac{3}{43}\)) between the median of C and the median of D is not realistic.
Med C - Med D = 3/43
Since the denominator of the difference of the medians is a prime number (43), the denominators of the medians of both C and D are either 43 or its multiples.
Now we need to get 3/43. How do we get it? Thats a tough calcalation. I did some excel calculation for the values of C and D. I could not get 3/43 from none of the median values for C and D.
In my answer below, I just know that it's impossible to find medians of C and D, and even we have g != f (both statements), there's no difference because you can divide 3 cases f=g, f<g, f >g when you find C and D in 2). In fact, with f=g+1 and the statement 2), I can prove that C and D don't exist
mnpqxyzt
2) median of C is 1/c or (1/c1 + 1/c2) /2 median of D is 1/d or (1/d1 + 1/d2) /2
We may have 1/c - 1/d = 3/43 (1) or (1/c1 + 1/c2) /2 - ((1/d1 + 1/d2) /2) = 3/43 (2) or 1/c - ((1/d1 + 1/d2) /2) = 3/43 (3) or (1/c1 + 1/c2) /2 - 1/d = 3/43 (4) we can not find c and d with only one equation like that so insufficient
C is the finite sequence \(C_1\)=0,\(C_2\)=\(\frac{1}{2}\),\(C_3\)=\(\frac{2}{3}\)...determined by the equation \(C_f\)=\(\frac{f-1}{f}\)where f is a positive integer.D is a similiar finite sequence determined by the equation \(D_g\) = \(\frac{g}{g+1}\) where g is a positive integer,Is the sum of allthe values in C equal to the sum of all the values in D?
1.g \(\neq\)f 2.The difference between the median of C and the median of D is \(\frac{3}{43}\)
Phew this took a while to type!Anybody with a detailed explanation?
Show more
I am not going into the logic of whether we can calculate the value of difference in median =\(\frac{3}{43}\) as it is not feasible to do in the GMAT exam. Let me tell the method that i followed here so that you can check with me back if it is not understandable.
IMO E because From the stem, we can deduce the following
We can see that the sum of terms in C and D are the same iff g=f+1 ; For all other values it is different. (1) f # g --> Not Sufficient (2) Difference between median of C and D is 3/43 . This is nothing but the difference between (Median+1)th term and median th of C. Hence, we can calculate Median of C. Similarly, we can calculate median of D ( as median th term and (median-1) =3/43) . Knowing the median won't help us.
(1) +(2) => We still cannot find the value of Sum as it can be equal if g=f+1 and not equal for all other cases.
Thus answer should be E
P.S : i understand your difficulty in typing fractions .
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