The fractional enantiomeric excess in favour of R is 82.88/112=0.74. Let fractions be r and s: r+s=1 and r−s=0.74. Subtract to obtain 2s=0.26, hence s=0.13. The sample contains 13% S and 87% R; optical purity 74% is not the minor-enantiomer percentage.
More Stereochemistry: Chirality and symmetry of organic molecules with or without chiral centres and determination of their absolute configurations and optical purity. Relative stereochemistry in compounds having more than one stereogenic centre. Homotopic, enantiotopic and diastereotopic atoms, groups and faces. Conformational analysis of acyclic and cyclic compounds. Geometrical isomerism and optical isomerism. Configurational and conformational effects, atropisomerism, and neighbouring group participation on reactivity and selectivity/specificity. Stereoselective and stereospecific synthesis. Enantiomeric excess. questions