A thermograph measures the infrared radiation from each small area of a person’s skin. Because the skin over a tumor radiates more than skin from nearby areas, a thermograph can help detect cancer cells. The emissivity e (in %) of radiation as a function of skin temperature T (in K) is e = f (T) = 100(T⁴ − 307⁴)/307⁴, if nearby skin is at 34°C (307 K). Find e for T = 309 K.