Sex Social class Average number Total BOTH SEXES Total Average 17.84 BOTH SEXES Total Standard deviation 4.22 BOTH SEXES I Average 17.69 BOTH SEXES I Standard deviation 4.10 BOTH SEXES II Average 17.73 BOTH SEXES II Standard deviation 3.83 BOTH SEXES III Average 17.80 BOTH SEXES III Standard deviation 3.84 BOTH SEXES IV Average 17.71 BOTH SEXES IV Standard deviation 4.07 BOTH SEXES V Average 17.75 BOTH SEXES V Standard deviation 4.22 BOTH SEXES VI Average 18.36 BOTH SEXES VI Standard deviation 5.08 BOTH SEXES No data recorded Average 18.34 BOTH SEXES No data recorded Standard deviation 4.28 MALES Total Average 17.10 MALES Total Standard deviation 3.17 MALES I Average 17.10 MALES I Standard deviation 2.89 MALES II Average 17.36 MALES II Standard deviation 3.77 MALES III Average 17.15 MALES III Standard deviation 3.01 MALES IV Average 17.16 MALES IV Standard deviation 3.45 MALES V Average 16.95 MALES V Standard deviation 2.90 MALES VI Average 17.23 MALES VI Standard deviation 3.58 MALES No data recorded Average 17.00 MALES No data recorded Standard deviation 2.09 FEMALES Total Average 18.80 FEMALES Total Standard deviation 5.14 FEMALES I Average 18.47 FEMALES I Standard deviation 5.19 FEMALES II Average 18.14 FEMALES II Standard deviation 3.86 FEMALES III Average 18.54 FEMALES III Standard deviation 4.48 FEMALES IV Average 18.62 FEMALES IV Standard deviation 4.80 FEMALES V Average 18.94 FEMALES V Standard deviation 5.42 FEMALES VI Average 19.54 FEMALES VI Standard deviation 6.04 FEMALES No data recorded Average 19.25 FEMALES No data recorded Standard deviation 5.07