A pot of boiling soup with an internal temperature of 100° Fahrenheit was taken off the stove to cool in a 67°F room. After fifteen minutes, the internal temperature of the soup was 95°F.
To the nearest minute, how long will it take the soup to cool to 85°F?
Using Newton's Law of Cooling - any of the following 3 formulas: , you
should find that it'll take the soup: to cool to a temperature of 85oF.