Question 1100432
-2.7x^2+30x+6.5=y
at 3 seconds
-9(2.7)+90+6.5=72.2 feet.
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-2.7x^2+30x+6.5=75
-2.7x^2+30x-68.5=0 
since approximate is desired, graph it.  
{{{graph(300,300,-3,12,-10,100,-2.7x^2+30x+6.5,75)}}}
3 and 8 seconds. We know 3 seconds is approximate from the first, and f(8)=73.7.
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on the way up need the vertex, which has a t value of -b/2a, and that is -30/-5.4 or 5.6 seconds.  Same time down.