b) When will the​ projectile's height above ground be at least 480 ft?

Question

If an object is given an initial velocity straight upward of v₀ feet per second from a height of s₀ ​feet, then its altitude s after t seconds is given by the formula s=−16t2+v₀t+s₀. A projectile is launched straight up from ground level with an initial velocity of 272 ​ft/sec.

b) When will the​ projectile's height above ground be at least 480 ft?

__seconds ​(Type your answer in interval​ notation.)

Answer 1

480 ≤ -16t² + 272t + 0

Can you solve for t and answer?