Question 1195453
{{{y=25x - 5x^2}}}

if {{{y=27.5}}}

{{{27.5=25x - 5x^2}}}

{{{5x^2- 25x+27.5=0 }}}........simplify, divide by {{{5}}}

{{{x^2- 5x+5.5=0 }}}...........use quadratic formula


{{{x = (-(-5) +- sqrt( (-5)^2-4*1*5.5 ))/(2*1) }}}

{{{x = (5 +- sqrt( 25-22 ))/2 }}}

{{{x = (5 +- sqrt( 3 ))/2 }}}


{{{x = (5 +- 1.732)/2 }}}


solutions:

{{{x = (5 + 1.732)/2 }}} =>{{{x = 3.37}}}

or

{{{x = (5 - 1.732)/2 }}}=>{{{x = 1.63 }}}


 these two times are: {{{ 1.63 }}}seconds and {{{ 3.37}}} seconds


{{{ drawing( 600, 600, -10, 10, -10, 35, circle(1.63,0,.123),circle(3.37,0,.123),locate(4,29,green(y=27.5)),
circle(1.63,27.5,.123),circle(3.37,27.5,.123),blue(line(1.63,0,1.63,27.5)),blue(line(3.37,0,3.37,27.5)),locate(1.4,-0.5,blue(1.63)),locate(3.2,-0.5,blue(3.37)),
graph( 600, 600, -10, 10, -10, 35, 25x - 5x^2, 27.5) )}}}