Twoinsulating materials of thermal conductivity K and 2K are available for Jagging a pipe carrying a hotfluid. If the radial thickness of each material is the same.

material with higher thermal conductivity should be used for the inner layer and one with lower thermal] conductivity for the outer.

material with lower thermal conductivity should be used for the inner layer and one with higher thermal] conductivity for the outer.

it is immaterial inwhich sequence the insulating materials are used

it is not possible to judge unless numerical values of dimensions are given.