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An observation deck extends 457 feet out above a valley. The deck sits 407 feet above the valley floor. If an object is dropped from the observation deck, its heighth in feet, after t seconds, is given by h= - - 161² + 2 +407. How long will it take for the object to be 7 feet above the valley floor? It will take 4.13 seconds for the object to be 7 feet above the valley floor (Type an integer or a decimal)

User Frogblast
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The height equation:


h=-16t^2+407

We want to know how long it will take [t] for the object to be 7 feet above the floor.

So, we substitute 7 into h and solve the equation for t. Shown below:


\begin{gathered} 7=-16t^2+407 \\ 16t^2=407-7 \\ 16t^2=400 \\ t^2=(400)/(16) \\ t^2=25 \\ t=\sqrt[]{25} \\ t=5 \end{gathered}

Thus, after t = 5 seconds, the height of the object is 7 feet above valley floor.

User Xiaomin Wu
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