



 
Hello Lori, Where ‘T’ is the temperature of the object at time ‘t’, and T_{s} is the temperature of the surroundings. (All this statement says is that the change in temperature of the object is proportional to the difference in temperature of the object and its surroundings.) Using a little calculus we obtain the equation,
We solve for ‘k’ by noting that the temperature was 70 after 5 minutes. So,
Rearranging and taking logarithms we get, Thus, our final equation is given by 70 = 80 e^{0.094t} + 20. Plug T = 20 in to find the temperature of the water after 20 minutes. Tyler  


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