body liquid percentage

According to this site it's somewhere in the range of 60%.

http://www.sws-sssd.org/water.html

This other site lists the average remains post-creamation as weighing between 4 and 6 lbs (1.8 to 2.7 kg). Maybe there is something being counted in one measure that isn't in the other. Who knows...

http://www.cremation.org/faq.html

Most of the cells are a bag of fluid with a small amount of solid material in solution or suspension. LIving bone averages perhaps 20 % liquid, There is about 1/2 gallon of blood and perhaps and almost that much other fluids including an average amount in the digestive track. All of these contain some dissolved and suspended solids, so 60% liquid seems reasonable.
In high temperature cremation, most of the carbon becomes carbon dioxide, and many of the compounds are decomposed and oxidized. The ash that remains is mostly metal oxides and phosphates, so 2 or 3 kilograms of ash seems reasonable, depending partly on how hot for how long. Neil