If X = a + b, the maximum percentage error in the measurement of X will be
Δaa+Δbb×100%
Δaa+b−Δba+b×100%
Δaa+b+Δba+b×100%
Δaa×Δbb×100%
X=a+b⇒ΔX=Δa+Δb Now ΔXX×100=(Δa+Δb)a+b×100 =Δaa+b+Δba+b×100