A worker at the top of a deep well, drops a hammer into the well. The hammer takes 2.81x10^-2 minutes to fall. How deep is the well?

There is a formula for the distance an object falls vs. time. You must have seen it before.

Distance = (1/2) g t^2 + Vo*t

That is the one to use.

Assume the initial velocity Vo is zero. That makes the problem even simpler.

I recommend converting the time of 0.28 minutes to seconds and using g = 9.8 m/s^2