why does an orange float with it's peel, but sinks when the peel is removed?

ANSWER: (http://wiki.answers.com/Q/Why_do_oranges_float)

Oranges float because with their peel on, their density is less than 1. The density of water is 1, and anything with a density less than 1 will float. However, if the peel is removed, the density will be more than 1, and the orange will sink.

The formula for finding density is:

Mass ÷ Volume=Density

orange image:http://images.google.com.sg/images?hl=en&q=orange%20peel&um=1&ie=UTF-8&sa=N&tab=wi