Data Sufficiency

Hi OptinumGMAT,

This question is based on the rules of 'rounding': when a digit is 0-4, you round the digit that is to the immediate left DOWN; when the digit is 5-9, you round the digit that is to the immediate left UP.

For example:

1.24, when rounded to the nearest tenth is 1.2

1.368, when rounded to the nearest hundredth is 1.37

We're told that K=4.2XY56, where X and Y represents single digits. We're asked for the value of X.

1) When K is rounded to the nearest tenth, the result is 4.3

Since we're rounding to the nearest TENTH, which is UP from 4.2 to 4.3, X must be an integer from 5-9, inclusive. However, we don't know the exact value.
Fact 1 is INSUFFICIENT.

2) When K is rounded to the nearest hundredth, the result is 4.27

Since we're rounding to the nearest hundredth, we're either rounding up OR down, so X could be 6 or 7.
Fact 2 is INSUFFICIENT.

Combined, we really don't have any additional work to do. There are two possible values that fit BOTH Facts: 6 and 7. We still don't know which one is the value of X though.
Combined, INSUFFICIENT.

Final Answer: E

GMAT assassins aren't born, they're made,
Rich

If anyone is interested, a video solution to this question can be found here: https://www.gmatprepnow.com/module/gmat ... video/1064

Cheers,
Brent