Question

the Antarctic ice cap contains some 6,300,000 cubic miles of water. Estimatehow much the sea level would rise if this ice cap melted ?

Answer 1

Let S be the surface area of the oceans and
W = volume of Antarctic ice cap.

Then the oceans will rise by approximately
W/S

An estimate of S is
S = 3.6×10^8 km^2

Now you just need to be careful of units.