C varies inversely as J. If C = 7 when J = 0.7, determine C when J = 12

Answer 1

C varies inversely as J ---> C = k(1/J) , where k is a constant
when C=7, J=.7
7 = k(1/.7)
k = 4.9

so C = 4.9/J
when J=12
C = 4.9/12 = .408333..

or:

C1/C2 = J2/J1
7/C2 = 12/.7
12C2 = 7(.7)
C2 = 7(.7)/12 = .408333..

notice the actual calculations are of course the same.