Differential Equation Free Fall

http://i.imgur.com/LSN5GfZ.jpg

Only need to see if my answer for number 1 is correct.

http://i.imgur.com/6S5KqC6.jpg

I didn't finish the last steps, but does all of this look correct? I got a time of about 3.2 seconds for the 400 pound object to fall 500 feet.