Suppose F varies jointly as x and y and inversely as z squared. If F is equal to 18 when x = 4, y = 3 and z =

Suppose F varies jointly as x and y and inversely as z squared. If F is equal to 18 when x = 4, y = 3 and z = 2, find the value of F if the values for x, y, and z respectively are doubled.