resistances of wires! could you help me with this?

Question

i have to get this right! so, please help me with this ok? thanx.

question: The light-duty extension cords that are routinely sold use are made from 18-gauge copper wire. Cords for higher current usage are often made from 16-gauge wire. Compute the resistances of wires 5.00 m long. The cross-sectional area of 18-gauge wire is 0.8231 millimeter square(mm2), and that of 16-gauge wire is 1.309 millimeter square.

Answer 1

R=(A/L)Cr
R- resistance
A - area of the conductor
L - length of the conductor
Cr - coeff of resistivity

Coper is 1.72 × 10−8 ohms meter at 20 C

R(16 ga)=[1.309 E-3)^2 / 5] 1.72 × 10−8
R(16 ga) = 5.89 E-15 ohms

R(18 ga)=[0.8231 E-3)^2 / 5] 1.72 × 10−8
R(18 ga) = 2.33 E-15 ohms

Answer 2

p=resistivity of copper=1.72*10^(-6) ohm-cm
ohm=p*length/area
p=1.72*10^(-6)ohm-cm*10mm/1cm
=17.2*10^(-6)ohm-mm
length=5m*1000mm/1m
=5000mm
#18
ohm=17.2*10^(-6)*5000/0.8231
=0.104483
#16
ohm=17.2*10^(-6)*5000/0.1.309
=0.065699