Question 1202374
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<pre>

The catapulted person touches the lake when its height is zero.


Therefore, the equation to solve is THIS

    -16t^2 + 50t + 20 = 0.


To solve it, simplify it first

    8t^2 - 25t - 10 = 0,

then apply the quadratic formula

    {{{t[1,2]}}} = {{{(25 +- sqrt(25^2 - 4*8*(-10)))/(2*8)}}} = {{{(25 +- sqrt(945))/16}}}.


We deny the negative root and accept the positive root  t = {{{(25 + sqrt(945))/16}}} = 3.48 seconds  (rounded).
</pre>

Solved.


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