86.34 minutes was used to cool the soup to 80 °F
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How can we calculate this using Newton's Law of Cooling?</h3>
Newton's Law of Cooling can be computed as :

The initial temperature is been represent by T0 which is ( 100 F)
The temperature of surrounding is been given as (69 F)
The final temperature is been given as T
t = time
we were told that the temperature of the soup move to 95 F, using 15 minutes.
Hence, T = 95 F
t = 15 min
Then we can input the values into the above equation as :

if we simplify this , we have

Then 
Then we can find the value of k as :
k= -0.012
Then we have the new equation as


Then at T=80F
we have,

t=86.34
Then if we simplify , we have t=86.34 which implies that 86.34 minutes was used to cool the soup to 80 °F
Learn more about Newton's Law of Cooling at:
brainly.com/question/17051432
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