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Celsius to Fahrenheit

Date: 04/26/99 at 20:05:42
From: Jessica
Subject: Celsius and Fahrenheit question

One January night at 9:00 p.m. the temperature was -3 degrees Celsius.  
Between 9:00 p.m. and midnight the temperature dropped 6 degrees.  
Between midnight and 10:00 a.m. the temperature rose 8 degrees. By 
noon the temperature had dropped another 4 degrees. What was the 
temperature at noon? Now here's the difficult part: Give the noon 
temperature in degrees Fahrenheit, not in degrees Celsius.

I got the first portion done. The answer would be -5 degrees, right?  
But I don't have a clue about how to answer the second portion. How do 
you get the Celsius into Fahrenheit?

Date: 04/29/99 at 11:59:58
From: Doctor Jeff
Subject: Re: Celsius and Fahrenheit question

Hello, Jessica.

Good job on the first part of the problem. For the second part, there 
is a formula to convert between Celsius and Fahrenheit.

     F = (9/5)*C + 32, where F is degrees Fahrenheit and C is degrees 
Celsius [Note that "*" means "times." Also, (9/5) = 1.8, if that 
makes calculations easier.]

For example, if the temperature is -10 C, you would get:

     F = (9/5)*(-10) + 32
       = -18 + 32
       = 14

You might be wondering whether this formula always works. You can try 
out some of the following well-known Celsius temperatures to check:

Freezing point of water: 0 C
Human body temperature: 37 C
Boiling point of water: 100 C

You should get familiar temperatures for these. If you want to 
convert from Fahrenheit to Celsius, just solve the formula for C:

     F - 32 = (9/5)*C
     (5/9)*(F - 32) = C, so
     C = (5/9)*(F - 32)

If the temperature is 14 F, then you should get
     C = (5/9)*(14-32)
       = (5/9)*(-18)
       = -10

Good luck with the rest of the problem!

- Doctor Jeff, The Math Forum
Associated Topics:
Middle School Negative Numbers
Middle School Temperature

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