Extended solution

The bath mat and the floor have been in the bath room for a longer period of time. Therefore they do have the same temperature - room temperature.

However, the floor has 20times of the heat conductivity of the bath mat. Due to this high heat conductivity the material is able to transport heat much better than the mat. Usually, room temperature is at about 22°C, body temperature at 37°C. When Laura is standing on the floor her feet heat up the space which she is standing on. The heat energy is transported from her feet to the floor. Heat receptors in Laura's skin are able to register this transport. Therefore, it feels cold. When Laura is standing on the bath mat, the heat is transported away from Laura's feet much slower. Therefore, the bath mat feels much warmer than the floor.