# relative error

#### sally9306

##### New member
i couldn't get what is relative error and how can i get it.
The question was ' calculated area of a room is 174.2 square feet and actual area is 149.6. find realative error.'

#### Mrspi

##### Senior Member
sally9306 said:
i couldn't get what is relative error and how can i get it.
The question was ' calculated area of a room is 174.2 square feet and actual area is 149.6. find realative error.'

Did you look for a definition of "relative error?" I'm sure it is in your textbook.

http://www.ehow.com/how_4425529_calcula ... error.html

#### sally9306

##### New member
well, i read that, but i cant get it
is relative error = measured area/actual area ?

#### mmm4444bot

##### Super Moderator
Staff member
sally9306 said:
well, i read that, but i cant get it Can you form any questions for us about it?

is relative error = measured area/actual area ? Nope.
That reference says, "[Relative error is] defined as the absolute error divided by the true value."

That reference also says, "To compute the absolute error, the difference between measurement and the true value is taken."

In your exercise, the measurement is 174.2 and the true value is 149.6, so their difference is the absolute error.

$$\displaystyle \text{Relative Error} \;=\; \frac{\text{Absolute Error}}{\text{True Value}}$$

#### AngelLovee

##### New member
Here's my problem

measured cube is 2cm actual length 2.1

So i would do 2-2.1 then divide it by 2.1?

#### Denis

##### Senior Member
Who you, Angel or Sally?