Express -40 degree C in degree F.Multiple Choice: A) -72 degree F B) -54 degree F C) 40 degree F D) 4.4 degree F

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pohnpei397's profile pic

pohnpei397 | College Teacher | (Level 3) Distinguished Educator

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The correct answer to this question is C -- the temperature is expressed as 40 degrees F.

The formula for converting from Celsisus to Fahrenheit is

Tf = 1.8*Tc+32  where Tf is the temperature in Fahrenheit and Tc is the temperature in Celsius.

You'll often see this expressed as (9/5)*Tc+32, but that's the same thing because 9/5 = 1.8

When you multiply -40 by 1.8 you get -72.  Then you have to add 32 to that.  That gives you -40.

So in this case, the temperatures are the same in Fahrenheit and Celsius.

krishna-agrawala's profile pic

krishna-agrawala | College Teacher | (Level 3) Valedictorian

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In centigrade system of measuring temperature (C), melting of ice/water  is taken as 0 C, and 1/100 division of difference in temperature of melting of ice and boiling of water is taken as 1 degree. In Fahrenheit system of measuring temperature (C), melting of ice/water  is taken as 32 C, and 1/180 division of difference in temperature of melting of ice and boiling of water is taken as 1 degree.This means magnitude of each degree F is equal to 9/5 times degrees C.

Thus we can convert any temperature in Fahrenheit in to centigrade using the following formula:

F = C*9/5 + 32

Therefore when C = -40, F is given by:

F = -40*9/5 + 32 = -72 + 32 = - 40

Answer:

- 40 C = - 40 F

None of the multiple choices given correspond to this answer.

Perhaps, by mistake, the value given in choice C) is 40 degrees F instead of -40 degrees F.

neela's profile pic

neela | High School Teacher | (Level 3) Valedictorian

Posted on

 

The Fahtenhiet scale begins with the temperature of 32, the ice melting point and ends with 212 , the water boiling point.The Centigrade scale starts with 0 degree as ice melting point and ends with 100 dgree as water boiling point. So the conversion  from -40 deg C to F is as follows:

(F-32)/(212-32) = (C-0)/(100-0) or,

(F-32)/180 = C/100.

Therefore,

F = (180/100)C +32. Put C = -40

F = (180/100)(-40)+32 = -40  degree in F.

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