Q.

Four persons measure the length of a rod as 20.00 cm, 19.75 cm, 17.01 cm, and 18.25 cm. The relative error in the measurement of average length of the rod is:      [2026]

1 0.08  
2 0.18  
3 0.24  
4 0.06  

Ans.

(4)

mean=1+2+3+44

mean=20.00+19.75+17.01+18.254

= 18.75

Δmean=|Δ1|+|Δ2|+|Δ3|+|Δ4|4

=1.25+1+1.74+0.54=1.12

So, relative error

=Δmeanmean=1.1218.75= 0.06