Done! 570 ('08) to 620 ('09) to 680 ('10) -updated - Debrief

Finally done with GMAT. Although it falls short of my target score, i will take it. I will post a debrief soon as i am off to a airport with only passport in hand :) Thanks outreach and makkwende. Here is my debrief. --------------------------------------------------------------------- I took GMAT l...

Can someone explain why A is insuff and B is suff. I am having hard time figuring it out.
Thanks

or you can solve it (for you understanding) using SD formula.

SD^2 = ((x1-x)+(x2-x)+(x3-x)+......+(xN-x))/N

where x is the mean of x1,x2,......,xN

take 3 numbers and solve the result will always be the std deviation itself when all terms are added with a constant.

Given p = POSITIVE, ODD and INTEGER what is the remainder of p/4? 1) p/8 leaves remainder 5 or p=8q+5 substitute q=0,1,2,3 we get 5,13,21 and so on dividing each of the above with 4 gives us 1 hence SUFF 2) p=a^2 +b^2 given p is odd we know E=O+E or E+O substitute integers in the above like a=2 and ...

This can also be solved using Venn diagram.

If OA is A

I can provide an explainer.

Is it A

Given x<y<1

1) (x + y)(x – y) = 5

RHS = +5

so 2 combination are possible

-5X-1 or -1X-5

this means x=-3 and y=-2

SUFF

2) xy=6
possible cases -1 and -6 or -3 or -2

INSUFF

Hence A

I took a cue from another problem i looked earlier in PS section. Statement 2 says -- 23x+21y=130 (x is no of 23 cents pencil and y is no of 21 cents pencils) multiples of 23: 23, 46 , 69, 92 etc multiples of 21: 21, 42, 63, 84 , 105 etc here 46+84=130 hence y=2 which gives us the answer, hence B

My take on it -- Let rate be R Given R propotional to A^2 propotional to 1/B In other words we can say R = [K (A^2)]/B -- (1) where K is some constant now B is increased to 100% ==>2B New Rate R' = [K (A'^2)]/2B -- (2) (A' is the new concentration) Required from Question stem R=R' [K (A^2)]/B = [K (...