x is a positive integer, is x even

coolgirl26 wrote:I'm really slow at solving for these type of data sufficiency questions

Please help me increase my speed by giving me some short cut to solve problem

X is a positive integar, is x even??

1) 9x^2 is divisible by 4 (meaning that 9x2 must be a multiple of 4..right..


divisible by 4 means 9x^2 is even,

Square if even means 9x is also even ( Try 4 is even, 2 is even, 9 is odd, 3 is odd)

9x is even

A product is even when atleast one of them is even

hence x must be even to make 9x even

Sufficient


2) 3x+2 is diviisble by 8


divisble by 8, 3x+2 is even

An addition is even when both adding elements are same ( either both odd or even)

2 is even, so to make 3x+2 even, 3x has to be even, and to make a product even, atleast one of the element has to be even

so x is even

Sufficient

choose D

Take aways

know when a product or additon results in odd or even

A square or cube resembles the properties of the number it is square or cube of..

HTH