Max@Math Revolution wrote:If 5-√5<x<5+√5, x=?

1) x is an even
2) √x is an integer.


* A solution will be posted in two days.

Given, 5-√5<x<5+√5

i.e. 5-2.1<x<5+2.1

i.e. 2.9<x<7.1

Question = ?

Statement 1: x is even
i.e. x may be 4 or 6 hence
NOT SUFFICIENT

Statement 2: √x is an integer
i.e. x is a perfect square between 2.9 and 7.1
i.e. x can only be 4, Hence,
SUFFICIENT

Answer: Option B

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

If 5-√5<x<5+√5, x=?

1) x is an even
2) √x is an integer.


In the original condition, x=4,5,6 is derived from 2.blabla<x<5.blabla. Then, there is 1 variable, which should match with the number of equations. So you need 1 equation, which is likely to make D the answer.
For 1), x=4,6, which is not unique and not sufficient.
For 2), x=4, which is unique and sufficient.
Thus, B is the answer.