Strongt wrote:If 4/x<1/3 what is the possible range of values for x?
in case 1:
x > 0
4/x < 1/3
12>x
It says on the MGMAT Guide: If x and y are positive then flip the inequality if 1/3 > 1/5 then 3 < 5
and assumming both sides are positive in case 1, i flipped the inequality
What am I missing here?
To apply the reasoning suggested by the guide, we need to flip not only the direction of the inequality but also EACH FRACTION:
4/x < 1/3 ---> x/4 > 3/1.
Thus:
x/4 > 3
x > 12.
Another approach: When the inequality is restricted to positive numbers, we can simply cross-multiply :
4/x < 1/3
3*4 < x*1
12 < x.
I favor this approach because it does not require that we flip the direction of the inequality.
Last edited by
GMATGuruNY on Fri Dec 16, 2011 8:14 am, edited 1 time in total.
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