Question 860815
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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) ={{{ 1/20 + 1/20 + 1/20 + 1/20 = 4/20 = 1/5}}}