Application of Differential Equation: Newton's Law of Cooling

At 2:00PM, a thermometer reading 80°F is taken outside where the air is 20°F. At 2:03PM, the temperature reading yielded by thermometer is 42°F, later the thermometer was brought inside where the air is at 80°F, at 2:10PM the reading is 71°F. When was the thermometer brought indoor?