SOLUTION: The temperature of a roast varies according to Newton's Law of Cooling: dT/dt= -k(T-A), where T is the water temperature, A is the room temperature, and k is a positive constant. I

Question 1085510: The temperature of a roast varies according to Newton's Law of Cooling: dT/dt= -k(T-A), where T is the water temperature, A is the room temperature, and k is a positive constant. If a room temperature roast cools from 68�F to 25�F in 5 hours at freezer temperature of 20�F, how long (to the nearest hour) will it take the roast to cool to 21�F?
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!

Let's do a substitution,

So then,

and

So,

and

or approximately,

So,

Find t when T=21.

to the nearest hour.

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