C= 5/9 (f-32)

For an experiment, a liquid is kept in cold storage at a temperature of 20 degrees Fahrenheit. The liquid is removed from cold storage and is warmed at a constant rate of 3 degrees Fahrenheit per hour. Which of the following represents the temperature of the liquid, in degrees Celsius, t hours after it has been removed from cold storage.

A) (5/3)t – 20/3

B)(5/3)t -188/9

C) (5/9)t – 20/3

D)(27/5)t +68

E) 3t +20

First, do the easy part: write the expression for the temperature in Fahrenheit.

20 + 3t

That whole expression is the temperature in Fahrenheit after t hours, so we need to put that whole expression into the conversion to Celsius.

C=\dfrac{5}{9}(20+3t-32)

C=\dfrac{5}{9}(3t-12)

C=\dfrac{15t-60}{9}

C=\dfrac{5t-20}{3}

C=\dfrac{5t}{3}-\dfrac{20}{3}

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