Resistance in a copper wire?

Question

The resistance R of a copper wire is proportional to the length L and inversely proportional to the cross section (area) A. Suppose a certain wire has resistance of 5.50 ohms. What is the resistance of a second wire which has twice the length and half the diameter of the first wire?

Answer 1

Doubling the length will double the resistance.

Since A = 2pi * r^2, halving the diameter will reduce the cross section to 1/4 of its original value which will quadruple its resistance.

Doubling and quadrupling at the same time will increase the resistance by 8 times to 44 ohms.

Answer 2

twice the length means twice the resistance, half the diamete means a quarter of the cross sectional area, so the answer is 8 times more resistance

44 ohms