Challenge Data Sufficiency Question

[Jim@StratusPrep]

You will have to click on the image to see the problem:




Try this one... OA to come after a few cracks at it from the community.[/img]

[svd.kumar]

1) x = -2, y = 1
x^4 > y^4, but x < y
x = 2, y = 1
x^4 > y^4, but x >y

2) x = 1 y = -32
5th Root(x) > 5th Root(y) and x > y
x = 32 y = 1
5th Root(x) > 5th Root(y) and x > y
x = -1 y = -32
5th Root(x) > 5th Root(y) and x > y

IMO B , I think main logic here is to understand significance of sign change with even and odd power

Thanks Jim good one. Correct me if i miss anything.

[jrakhe]

My answer is B.

This question is testing the Odd Vs Even powers, please correct me if I am wrong

[Jim@StratusPrep]

You guys are right, but be careful with exponent inequality DS questions... Always test between 1 and 0 and -1 and 0...

[chuotsmart]

For (2), I tested with those: (32, 243); (-32, -243); (1/32, 1/243); and (-1/32, -1/243). They indicated that (2) was sufficient. However, it took more than 2 mins to execute the tests. Would you recommend any shortcut? Thank you!

[dhonu121]

My office network isn't allowing the link to be opened
Wish you could have posted the question so that even I could have attempted it.

[Jim@StratusPrep]

Sorry... Had a 5th root in the problem so the only way to do it was with an image...

[Jim@StratusPrep]

Also... for those who are looking for a quick way to solve this think about the numbers shifting. When you take an odd root of a number it shifts on the number line. Higher if less than -1, Lower if between -1 and 0, Higher if between 0 and 1 and lower if greater than -1.

Even though you do not know the numbers, you can know that you will never get a "cross-over" when these numbers shift. For this reason, B is correct. The difference with A is that you can have positive and negative numbers for x and y because of the even power.

Hope this helps.