700plus2010

Hi, I need your help. I've a big problem with data sufficiency. e.g. In the sequence of 7 positive integers 2, 3, k, r, 7, 7, 11 if the average equals the median, which is one of the members in the sequence. What is the average? (1) r=6 (2) k=r I go for D as if I insert 6 in the sequence above it is my median. The question says that median=average so I can set up the equation: 2+3+k+6+7+7+11)/7=6 as I know that the median is r (middle number out of 7) so stat. one is suff for me. No discussion about stat. 2 this is sufficient as well as I can insert 2k and build up an equation. But: OA is B :mad: I'd be also very grateful for some advice how to attack data sufficiency and how to improve systematically! Who can give me a detailed explanation?

Thanks Fiver. I did the same mistake as schyamo

thanks OA is C good explanations

I'm sorry. I think it's the same 1/2*X or 1/(2x) as it is multiplication? That's why I wrote the 2x in brackets... The same is for (2) It's (1/7)*x So you know how to solve that?

I'm sorry, but there is no more information available. I got this at a training. I could ask the teacher but I thought someone like you could solve it... It should train the basic knowledge of geometry. That ZY||AB is sth. I learned from a book that when ratio 2:1 is given the two sides should be parallel. I also know the answer. XZ=34 So somehow we should come to the result that XA or that XZ=XY. I really don't know.

Hi chix! You mean angle CTF = 90° right?! And then you say that a tangent is always perpendicular to the radius, right?! So no matter what angle CAT is I can always substract this from 90°?! Please correct me if my reasoning is wrong. The typo made me think deeper... Thanks a lot. I hope you can help me with my other geometry problems as well...

Hi, I'm not able to figure that out. I think I have to draw a right angle but then I stuck. Pleas help, thanks.

Hi, please see the graph and give me a hint. Thanks

What is the length of BA? Thanks in advance

Try to take smaller numbers to make it clear. Take 28 and 10. The even integers are: 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 If you add them all together you'll get: 190 You get the average when adding 28+10)/2 So 19 is exactly between 10 and 28, right. If you add 10 and 28 you make the range from 0 to 38 and division by two results in 19 - be careful it's not the same as 28-10 Now you need the no. of the terms: 28-10=18 (but also with odds) therefore divide by 2: 18:2=9 (now without odds) but as it says inclusive add 1: 9+1=10 Now the sum off all even integers between 10 and 28 is: 10*19=190 which is the same Hope this helps

If integer n is a two-digit number, is n divisible by nine? 1)When n is divided by three the remainder is two. 2)When n is divided by seven the remainder is one. What is the best approach? Thanks

devp, how do I know that (1+1)^91 = 91C0+91C1+...?

devp, Thank you so much! You have been a great help. Can you also help me out on the other "Remainder of sum devided by number" problem, I posted earlier.

Your even numbers go from 100 to 300 So add these two and take the average: 300+100)/2=200 The quantity of numbers are 100 to 300 inclusive: 300-100)/2)+1=101 Multiply 200 and 101 = 20200

Fiver, good explanation! Thanks

devp, why do you include the 3 into the multiplication for the remainder (3*1)? Why don't we add 3+1? Could you please elaborate on your remark "Now if we replace 9 by any..." a little If I understand you right you say: (5+5^2+...5^13)/10 will get me the same result? Or do you mean I will get 5. That's what I got. I think that's the same as fiver wrote in other words, right?! Thanks

I go with the above 3 and say B as well. 1) is true for both 0 and 1 2) is true for 0 What is OA?

If x=6386B and B is the units digit of x, what is the value of B? 1) 1/(2x) has a remainder of 1 2) 1/(7x) is an integer

What is the remainder when 9^1+9^2+...+9^9 is divided by 6? a0 b3 c4 d2 eNone of these

I don't know if this was a gmat problem. I got this question for learning. This way is too long to be a solution for the gmat if it was a gmat problem.

I also think B Take 7 out: all green take 9 out: all blue so now we have taken 16 out and there are still 2 green and 2 blue left. take another 4 out: now all green and blue are out. The next marble I pick has to be red. I "will be certain" that I took at least one marble. What is OA?

Hi clock 60, thanks a lot. I'm sorry. I had no choices either. Just this question...

Okay I will keep your advice in mind...

Thanks for your help. I just had the question not the choices...