W.F. Weeks and W.J Campbell in the Journal of Glaciology used a cubic model for towing a flat iceberg from Amery Ice Shelf in Antarctica to Australia. The equation is V=7.75-0.35x+0.0625x^2-0.0208x^3, where V is the number of cubic kilometers of ice remaining and x+3 is the number of thousand kilometers traveled by the iceberg, 0<x<4. The volume of ice changed very little in the first 3000 km of the tow, as it was little in the first 3000 km of the tow, as it was still in Antarctic conditions.

a) What was the initial volume of ice?

b) What was the volume of ice remaining after the iceberg had been towed 4000km (that is, when x=1)?

c) if the total length of the journey was 7000 km, what percentage of the original volume of ice still remained?

d) How many kilometers was the iceberg towed before it lost 10% of its volume?