NEED HELP ASAP!!!!!!!!

Question

A stuntman jumping off a 20-m-high building is modeled by the equation h = 20 – 5t², where t is the time in seconds. A high-speed camera is ready to film him between 15 m and 10 m above the ground. For which interval of time should the camera film him?

t < 2

Answer 1

The man jumps (therefore falls, unless he has superpowers) from a 20 m tall tower, and the equation that indicates his height at time t (assume meters for the units) is given as h(t) = 20 - 5t^2. The constant 20 in the equation and the tower height match, and therefore one can infer that the height function indicates the man's height above the ground (he loses height as time increases from t=0).

The question also indicates that the camera is to film him between 15 m and 10 m above the ground. Put in these values for the stuntman's height, and solve for the two limits of t. At 15 m, t is 1 s, and at 10 m, sqrt(2) or 1.414 s.

If you wish to skip calculations and zero-in on an answer, look for the answers that provide a range of time since a range in height is what the question provides... and choose wisely :-)