Please I need help: I need to figure out the procedure to this question:

Growth rate of odd size object:
Start: 1.5" w by 1.5" l by .25" h
End: 3.25" w by 3.50" l by .25" h
Did this object increase by 600%?
How do I figure this out?
Thank you very much,
Tracy

volume of first = 1.5(1.5)(.25) = .5625 cubic inches

volume of last = 3.25(3.5)(.25) = 2.84375

2.84375/.5625 = 5.055..

= 505.6%