Simple Physics Problem

I am taking AP Physics right now. The thing is, my teacher is really stupid, doesn't know physics, and missed the first 6 weeks of school because of her kid. This problem should be easy, I just don't know how to solve it.

A person throws a ball straight up in the air at 1.5 m/s. The ball lands 4 m below where it was originally thrown. How long is the ball in the air?

Thanks.

You know the equations of motion?

Namely:

Nevermind lol...

Edit: Just to make sure I'm right here, is the answer 1.62 seconds?

x-x0 = v0*t + 0.5*a*t^2

-4 = 1.5t - 4.9t^2

I'm getting 1.07s

What are you told to use for gravitational field strength?

The answer could differ by quite a bit depending on what you use.