SOLUTION: A cup of coffee is poured at 190ËšF and is allowed to cool in a 70ËšF room. If the temperature of the coffee is 170ËšF after half an hour, (a) What will the temperature be after

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Question 1160926: A cup of coffee is poured at 190ËšF and is allowed to cool in a 70ËšF room. If the temperature of the coffee is 170ËšF after half an hour,
(a) What will the temperature be after 70 minutes?
(b)How long it will take the coffee to cool to 120 ËšF?
Found 2 solutions by CubeyThePenguin, MathTherapy:
Answer by CubeyThePenguin(3113)   (Show Source): You can put this solution on YOUR website!
190 F after 0 minutes, 170 F after 30 minutes --> decrease of 2/3 degrees every minute

a) 190 - 70(2/3) = 430/3 = 143 1/3 degrees

b) 190 - (2/3)x = 120
70 = 2x/3
210 = 2x

x = 105 minutes
Answer by MathTherapy(10554)   (Show Source): You can put this solution on YOUR website!
A cup of coffee is poured at 190ËšF and is allowed to cool in a 70ËšF room. If the temperature of the coffee is 170ËšF after half an hour,
(a) What will the temperature be after 70 minutes?
(b)How long it will take the coffee to cool to 120 ËšF?
The other person, CUBEYthePENGUIN is WRONG!

You can use Newton's Law of Cooling to get a temperature of: 

In addition, to reach a temperature of 120oF will take  

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