Question 374292
{{{h=250t-4.9t^2}}}
Is a quadratic (parabola) that opens downwards.  We can tell because the coefficient associated with the t^2 term is negative.  If so, then the vertex defines the hight point.
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Highest point is reached when the time is:
t = -b/(2a) = -250/(2*(-4.9)) = -250/(-10.8) = 25.51
Highest point projectile will reach:
{{{h=250(25.51)-4.9(25.51)^2}}}
{{{h=3189 }}} meters
{{{h=3.189 }}} kilometers
.
So, now we can answer the question:
a)2.75km (yes)
b)4.0km (no)