Temperature on Earth is proportional to the fourth root of solar flux (T proportional to F?0.25),…

Temperature on Earth is proportional to the fourth root of solar flux (T proportional to F_0.25), and flux F is proportional to the Sun’s luminosity. If Sirius B, with a total luminosity of 0.055 L_, were substituted for the Sun, what would Earth’s average temperature become? (Note: Earth’s current average temperature is 287 K.)