A student carries out a titration three times and obtains the following volumes: \(3.0 \pm 0.1{\text{ c}}{{\text{m}}^3}\), \(3.2 \pm 0.1{\text{ c}}{{\text{m}}^3}\) and \(3.2 \pm 0.1{\text{ c}}{{\text{m}}^3}\). What is the average volume?

A.     \(3.1 \pm 0.1{\text{ c}}{{\text{m}}^3}\)

B.     \(3.13 \pm 0.1{\text{ c}}{{\text{m}}^3}\)

C.     \(3.1 \pm 0.3{\text{ c}}{{\text{m}}^3}\)

D.     \(3.13 \pm 0.3{\text{ c}}{{\text{m}}^3}\)

A

This was the second most difficult question of the paper. Most candidates answered C or D, not realizing that, if correct, repeats would then increase the uncertainty.