SOLUTION: Find the probability that the vertex of the graph y=x^2-8x+c is above the x-axis if the c is a randomly selected integer from 1 to 20. I've tried so many things and I just can'

Algebra ->  Probability-and-statistics -> SOLUTION: Find the probability that the vertex of the graph y=x^2-8x+c is above the x-axis if the c is a randomly selected integer from 1 to 20. I've tried so many things and I just can'      Log On


   



Question 860815: Find the probability that the vertex of the graph y=x^2-8x+c is above the x-axis if the c is a randomly selected integer from 1 to 20.
I've tried so many things and I just can't figure out how to even set up the problem. I'm just so confused and could really use some help.

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 
Hi,
y=x^2-8x+c
y = (x-4)^2 - 16 + c
To be above the y axis, c > 16
P(17 0r 18 0r 19 0r 20) =+1%2F20+%2B+1%2F20+%2B+1%2F20+%2B+1%2F20+=+4%2F20+=+1%2F5