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Graph Question - need expert help (probabaility)

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Graph Question - need expert help (probabaility)

by voodoo_child » Sun Sep 09, 2012 3:48 pm
What is the probability that abs(y) >x?

(Source MGMAT)


What would be the graph of |y| > x?

I used a graphing calculator -here's the graph

Image

However, if we say |y| > x => y> x for +ve values of x and -y > x for -ve values of x, we will get an intersection of a graph that looks like :

Image

Any reasons why there is such a difference. My mind is a bit exhausted, and I am not able to think of difference.....



thanks
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by pemdas » Sun Sep 09, 2012 4:42 pm
I think your question has trivial answer if you will use the slope facts of y function. When slope=0 we have horizontal line (exclude this one). Here we are looking into sub-sector 0-90` where the slope is positively downward/upward (from the right upper corner to the left bottom corner). When the slope is 1, i.e. y=x we have 45` and in all other cases we have |y|>x. So by allowing 90-45=45 and 45/90 is 1/2 we may state the probability will be 1/2 that |y|>x. Additionally we can include the -ve function results in mode and state p=1/2 because the slope is mathematically a tangent of the angle in right triangle formed by x-coordinate line and the line |y|=x itself ---> delta(y)/delta(x).
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by voodoo_child » Sun Sep 09, 2012 5:00 pm
all - Please ignore. I understood my mistake. there was an error in > and < sign.
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by voodoo_child » Sun Sep 09, 2012 5:01 pm
answer is 3/4 thanks
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