How Do You Calculate the Characteristic Impedance of a Transmission Line?

[Roodles01]

Homework Statement

Transmission line is designed so it has selfinductance, L = 7.0x10^-7 Hm^-1 & signal speed 70% of c
Find characteristic impedance

Homework Equations

Z = √L₀/C₀ Ω
also
v = 1/ √L₀C₀

The Attempt at a Solution

So
L = 7.0x10^-7 Hm^-1
v = 0.7c (c = 3x10^8 ms^-1)

7(3x10^8)/10 = 1/√7.0 * C₀
so
C₀ = √((10(7.0x10^-7))/(7*3x10^8))
C₀ = √ 3.33x10^-15
C₀ = 5.77x10^-8 F

Z = √L₀/C₀
Z = √7.0x10^-7/5.77x10^-8
Z = 3.4 Ω

Which isn't in the park as far as expected result goes, so AGAIN, please could you show me where I went wrong.

 

[Roodles01]

OK, OK I get it.
Forgot to square, but square rooted instead.
All sorted.