Question

A ball is thrown from an initial height of 3 feet with an initial upward velocity of 30/fts . The ball's height h (in feet) after t seconds is given by the following. h= 3+30t-16t^2 Find all values of t for which the ball's height is 16 feet. Round to the nearest hundredth

Answer 1

At 16 feet we have
16 = 3 + 30t - 16t^2

16t^2 - 30t + 13 = 0

t  = [- -30 +/- sqrt(30^2 - 4*16*13) ] / 32

t  = 1.20 , 0.68 seconds  answer   ( correct to the nearest hundredth)

Answer 2

0.68 or 70 I think not to sure