Time intervals measured by a clock give the following readings : 1.25 s, 1.24 s, 1.27 s, 1.21 s and 1.28 s What is the percentage relative error of the observations?

The arithmetic mean of given values is taken as true value.tmean =t1+t2+t3+t4+t55tmean =1.25+1.24+1.27+1.21+1.285tmean =1.25sΔtmean =Δt1+Δt2+Δt3+Δt4+Δt55Δtmean =0+0.01+0.02+0.04+0.035=0.02s Percentage error =Δtmean tmean ×100=0.021.25×100=1.6%