At the start of a basketball game, the referee tosses a ball into the air for the jump ball. The equation that models the height of the ball is h(t) = -16t2 + 30t + 8. During what time interval is the height of the ball above 10 feet? (Round your answer to the nearest tenth of a second.)
a) Between 0.3 and 2.1 seconds
b) Between 1.1 and 1.6 seconds
c) Between 0.1 and 1.8 seconds

Question

At the start of a basketball game, the referee tosses a ball into the air for the jump ball. The equation that models the height of the ball is h(t) = -16t2 + 30t + 8. During what time interval is the height of the ball above 10 feet? (Round your answer to the nearest tenth of a second.)
	a)	Between 0.3 and 2.1 seconds
	b)	Between 1.1 and 1.6 seconds
	c)	Between 0.1 and 1.8 seconds

ajprincess · Answer

substitute 10 h(t) then u will get
$$10=-16t^2+30t+8$$
$$16t^2-30t+10-8=0$$
$$16t^2-30t+2=0$$
Divide the whole eqn by 2.
then u will get
$$8t^2-15t+1=0$$
Nw solve for t using the formula
$$x=\frac{-b+/-\sqrt{b^2-4ac}}{2a}$$

ajprincess · Answer

Tell me wat u get when u solve?

anonymous · Answer

i got c

ajprincess · Answer

ya right. i too get the same. Is it clear to u?

anonymous · Answer

yah thanks :)

ajprincess · Answer

yw.:)
At 0.1sec and at 1.8sec it will be at 10ft height.bt between that time interval it will be at a height greater than 10ft.