The function y = - 16t 2 + 486 models the height y in feet of a stone t seconds after it is dropped from the edge of a vertical cliff. How long will it take the stone to hit the ground? Round to the nearest hundredth of a second. A. 5.51 seconds B. 0.25 seconds C. 7.79 seconds D. 11.02 seconds

Question

Mathematics

Krista Macdonald

17 March, 01:53

The function y = - 16t 2 + 486 models the height y in feet of a stone t seconds after it is dropped from the edge of a vertical cliff. How long will it take the stone to hit the ground? Round to the nearest hundredth of a second. A. 5.51 seconds B. 0.25 seconds C. 7.79 seconds D. 11.02 seconds

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Answers (1)

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Gracelyn Knight · Answer 1

That is when the height is 0

0=-16t^2+486

solve

add 16t^2 to both sides

16t^2=486

divide both sides by 16

t^2=243/8

sqrt both sides

t=5.511

round

t=5.51 seconds

answer is A