Hello,

We know that,

Equivalent Conductivity for parallel combination is given as,

Keq. = ( K1.A1 + K2.A2 ) / A1 + A2

where, K is the Conductivity and A is the Area

So, from given data, A1 = 0.2 and A2 = 0.3

Also, K1 = 60 and K2 = 40

So, Keq. = [ ( 60 x 0.2 ) + ( 40 x 0.3 ) ] / ( 0.2 + 0.3 )

So, Keq. = 24 / 0.5

So, Keq. = 48 Wmk

Hence, the effective conductivity is 48 Wmk

Best Wishes.