Question

During a practice match, a softball pitcher throws a ball whose height can be modelled by the equation $h=-16t^2+24t+1$,
where $h=\text{height in feet and}t=\text{time in seconds}$.
How long does it take for the ball to reach a height of 6 feet?

• A. 2.2, 3.8 secs
• B. 5.4,6.2 secs
• C. 0.25,1.25 secs
• D. 7,5 secs

Answer 1

The correct option is C

0.25,1.25 secs

Given Height = 6

$\Rightarrow -16t^2+24t+1=6$

$\Rightarrow 16t^2-24t+5=0$

$\Rightarrow (4t-1)(4t-5)=0$

$t=\frac{1}{4},\frac{5}{4}or0.25,1.25$

It takes 0.25 secs and 1.25secs for the ball to go up and down respectively.