2. Solve the following problems using differential equation. a. A thermometer reading T5 1* F is taken out where the temperature is 2D D F. The reading is 30 0 F 4 min. later. Find: (a) The temperature reading 7 min. after the temperature was brought outside. (b) The time taken for the reading to drop from T5 9 F to within a half-degree of the air temperature. b. The conversion of a substance B follows the law used simple chemical W If only a fourth of the substance has been converted at the end of 10 see, nd when nine-tenths of the substance will have been converted