Simple energy/kinematics problem

[maxbashi]

I'm not seeing my mistake, but I'm not getting the answer in the back of the book.

Homework Statement

A water slide has a height of 4.0 m. The people coming down the slide shoot out horizontally at the bottom, which is a distance of 1.5 m above the surface of the water in the pool. If a person starts down the slide from rest, neglecting frictional losses, how far from a point directly below the bottom of the slide does the person land?

Homework Equations

Just conservation of mechanical energy, and kinematics.

The Attempt at a Solution

The book gives 4.9 m, but here is my work where I get 3.9 m. I almost hate to ask what I'm doing wrong...

 

[gneill]

Recheck your calculation for the initial velocity. What's the change in height from the top of the slide to the bottom of the slide?

 

[maxbashi]

Oh - would the 4.0 m be the distance from the top of the water slide to the pool, or the distance from the top of the water slide to the bottom?

(Ok just answered my own question - thanks)