Using Newton's law of cooling with approximation, \\\\(\\dfrac{dT}{dt} = \\dfrac{-k}{ms} (T_{avg} - T_s)\\\\)Case 1 : \\\\(dt = 2\\\\) minutes; \\\\(T_s = 20\\\\) \\\\(T_{avg} =\\dfrac{94+86}{2} = 90\\\\) and \\\\(dT = 94-86 = 8\\\\)\\\\(\ herefore\\\\) \\\\(\\dfrac{-k}{ms} = \\dfrac{dT}{dt}.\\dfrac{1}{T_{avg}-T_s} = \\dfrac{8}{2\ imes 70} = 0.05714\\\\) .......(a)Case 2 : \\\\(T_s = 20\\\\) \\\\(T_{avg} =\\dfrac{74+66}{2} = 70\\\\) and \\\\(dT = 74-66 = 8\\\\)\\\\(\ herefore\\\\) Time in which it cools down \\\\(\\dfrac{8}{dt} = 0.05714\ imes (70-20)\\\\)\\\\(\\implies \\\\) \\\\(dt = 2.8\\\\) minutes