<PRE><B>Question 992225</B>
if a projectile is shot vertically upward from the ground with an initial velocity of 150 ft per sec. Neglecting air resistance, its height S (in feet) above the ground t seconds after projection is given by S=-16t^2 + 150t 
after how many seconds will it be 60ft above the ground? 
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S(t) = -16t^2 + 150t
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Solve:: -16t^2+150t = 60
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-8t^2 + 75t - 30 = 0
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t = 0.4187 or t = 8.956
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Cheers,
Stan H.</PRE>