Solving Pressure & Force Homework Problem

[vrobins1]

Homework Statement

"A lid is put on a box that is 10 cm long, 16 cm wide, and 8.0 cm tall and the box is then evacuated until its inner pressure is 7.2e4 Pa."

How much force is required to lift the lid at sea level?

Homework Equations

I know that I have to use P=F/A
I changed my centimeters to meters also, although I'm not sure you have to.

The Attempt at a Solution

I used F = PA
F= (Atmospheric pressure - inner pressure)(lxw)
F=(100000 - 72000)(.10x.16)
F=(28000)(.016)
F=448 N

I tried this answer but got it wrong. Can someone please point me in the right direction? Thanks!

 

[vrobins1]

I figured it out! I just used a more accurate number for my atmospheric pressure instead of simply 10000.