# Formula for Error Calculations

Posted in Dimensional Formulae | Email This Post |We have already shown how to calculate Absolute error, mean absolute error, relative error and percentage error in previous posts but the real problem arises when we have two quantities and we need to find out the combined errors.

Here are the formula’s to be used

Lets say we have three quantities a, b and x. The absolute errors in these are respectively + – Δa, + – Δb and + – Δx

Case 1 When x= a+b then Δx= +- [Δa+Δb]

Case 2 When x= a-b then Δx= +- [Δa+Δb]

Case 3 When x= axb then Δx/x= +- [Δa/a+Δb/b]

Case 4 When x= a/b then Δx= +- [Δa/a+Δb/b]

**Case 5 When x= a ^{n} b^{m}/ c^{o} then**

Δx/x = +- [nΔa/a+mΔb/b+pΔc/c]

awesome…thanks a lot…