Past exam of the year 2 of the earth sciences (geology) course of the University of Oxford / 2023 / Paper 1 / 9 / c / Solution

Squaring each seasonal standard deviation gives the seasonal variance in squared concentration units:

No unit is printed in the held table, so a numerical concentration unit should not be invented. The markedly smaller summer variance is also a warning when assessing the common-variance assumption of ordinary ANOVA.