Data Sufficiency

so A:B is 3:1 that's cool but is there anything like A:B -3:1 ?

Not sure; lets ask around...

If I come across something I will be sure to pass it along also

I think it's E either, M has two different values.

Logitech Please check if this works for you

m^2= 7/5

m^2/n= 7/5 => n=1


m/n^2 = SQRT(m^2/n^4)
=SQRT(7/5/1)
=SQRT(7/5)

So C

Tryingmybest wrote:Logitech Please check if this works for you

m^2= 7/5

m^2/n= 7/5 => n=1


m/n^2 = SQRT(m^2/n^4)
=SQRT(7/5/1)
=SQRT(7/5)

So C

I don't have any problem with finding the ratio. I am concerned with the two different values of the same ratio:

SQRT(7/5) and - SQRT(7/5)

Please help me understand y do we need - SQRT(7/5)

Could you please spot the logic error in my approach? It will be helpful to analyse.

Tryingmybest wrote:Please help me understand y do we need - SQRT(7/5)

Could you please spot the logic error in my approach? It will be helpful to analyse.

Well you know that every positive number have two square roots. So I guess sqrt(7/5) is samething with -sqrt(7/5)

what is confusing with ratios is, for example -4 and -2

Their ratio is -4/-2 = 2

But does it mean that -4 is 2 times greater than - 2 ? NOO

So I am not quite sure about the this negative rules with ratios but, I need some expert opinion.

Just like in beetlejuice, I want to say her name three times:

STACEY STACEY STACEY!

Looks like PM'ng an expert and waiting for a response is the option left

I dont have a convincing answer for you so I am going to wait and watch the explanation unfold for this....

cramya wrote:Looks like PM'ng an expert and waiting for a response is the option left

I dont have a convincing answer for you so I am going to wait and watch the explanation unfold for this....

In mathematics, a square root of a number x is a number r such that r2 = x, or, in other words, a number r whose square (the result of multiplying the number by itself) is x. Every non-negative real number x has a unique non-negative square root, called the principal square root, which is denoted with a radical symbol as \sqrt{x}, or, using exponent notation, as x1/2. For example, the principal square root of 9 is 3, denoted \sqrt{9} = 3, because 32 = 3 × 3 = 9. If otherwise unqualified, "the square root" of a number refers to the principal square root: the square root of 2 is approximately 1.4142.

Every positive number x has two square roots. One of them is \sqrt{x}, which is positive, and the other -\sqrt{x}, which is negative. Together, these two roots are denoted \pm\sqrt{x}. Square roots of negative numbers can be discussed within the framework of complex numbers. More generally, square roots can obviously be considered in any context in which a notion of "squaring" of some mathematical objects is defined (including algebras of matrices, endomorphism rings, etc).

Is 7/5 a real number or non-negative number ? :roll:

Ok I believe you can have a negative ratio. I mean the slope of a line is the ratio of the rise and run and you do have negative slopes.

I think a negative ratio of say x/y = -1.8/1 shows the negative correlation of x and y. If y increases by 1, x falls by 1.8.

Btw sqrt(7/5) = 1.8 or -1.8

So a negative ratio is possible.

so the answer is E

logitech wrote:so the answer is E

Logitech,

particularly in ratios, we always take positive ratios.
So, the ans shall be C.
Consider a case: ratio of boys to girls in a class is -4:3? Is it practically feasible? No. Yes, there are negative slopes but we cant apply that concept to ratios. Ratios are always positive numbers.
Hope it clears the air.

@jimmiejaz

A slope is a ratio. So if a slope can be negative, then ratios can also be negative.

Ratios are just plain fractions and fractions can be negative.

Declining speed is negative ratio (its called deceleration I guess) since speed is a ratio.

The ratio of boys : girls can't be negative I mean you can't have negative number of boys or girls right.

I believe negative ratios can be theoretically possible, but many cannot be practically possible.

Also a negative ratio shows a negative relationship between the 2 variables. As one variable increases the other decreases. Negative correlation.

jimmiejaz wrote:

logitech wrote:so the answer is E

Logitech,

particularly in ratios, we always take positive ratios.
So, the ans shall be C.
Consider a case: ratio of boys to girls in a class is -4:3? Is it practically feasible? No. Yes, there are negative slopes but we cant apply that concept to ratios. Ratios are always positive numbers.
Hope it clears the air.

jimmie,

how about dollar loosing its value 5 cents per day and euro is climbing up 4 cents per day

What is your ratio ?

i think we are mixing two concepts here.
Number properties with ratios. Yes the slopes can be related negatively or as you correctly pointed out deceleration but i dont think in gmatland we have anything like negative ratios.
So, we can say out of scope.

Would love to hear more on it from an expert though!!!!!!
Experts please help!!!

logitech,

In this case we will consider relative increase decrease....
we can say the total deflection is 9 cents
instead of putting -5:4