Cat 5 question 17

[sas.munshi]

What is the ratio of r to s
(1) r + s = 7

(2) r2 - s2 =7

Its a data sufficiency question and I chose B as (4+3)(4-3) =7.However the answer choice is C.
Can you please clarify if we are not supposed to do this.

[jnelson0612]

What is the ratio of r to s
(1) r + s = 7

(2) r2 - s2 =7

Its a data sufficiency question and I chose B as (4+3)(4-3) =7.However the answer choice is C.
Can you please clarify if we are not supposed to do this.

Yes, you are assuming that r and s are integers. However, since the problem does not state this they do not have to be.

For example, r could be 4 and s could be 3, as you stated. However, r could also be the square root of 8 and s could be 1. These numbers would also fit statement 2, and this would give us a different ratio.

[sas.munshi]

Thank you :)

[tim]

:)

[krishnan.anju1987]

I am unsure of whether I am mixing up basic concepts now or whether I am right on the track.

For B can we also assume r and s to be negative? For e.g r=-4, s=3, then r:s= -4:3. Can a ratio be negative? I was not sure whether I can do this but since r and s are not mentioned to be positive and these numbers to fit the criteria in 2) (r^2-s^2=7), I thought I could use this for eliminating B. Also, technically since ratios are fractions this should be possible but I am unsure how to convert it into a statement. For e.g. if a owes a debt of $ 5 and b is supposed to receive $ 10, then can I consider the ratio to be -5:10. Would this be an example of a negative ratio.

Any help to clear this up would be appreciated.

Thanks,
Kris

[tim]

negative ratios are fine, and there is nothing in this problem to prevent the numbers from being negative..