Two flow passages with different cross-sectional shapes, one circular another square, are each centered in a square

Question:

Two flow passages with different cross-sectional shapes, one circular another square, are each centered in a square solid bar of the same dimension and thermal conductivity. Both configurations have the same length, T₁, and T₂. Determine which configuration has the higher rate of heat transfer through the square solid bar for

(a) A = 1.2b

(b) A = 2b.