Blocking refers to the idea that the variability in a variable can be reduced by segmenting the data by some other variable. The data in the accompanying table represent the recumbent length(in centimeters) of a sample of 10 males and 10 females who are 40 months of age. Complete parts(a) through(d). (a) Determine the standard deviation of recumbent length for all 20 observations. ____ cm (Round to two decimal places asneeded.)

Males Males

103.0 94.4 102.5 100.8

93.7 97.6 100.0 96.3

98.7 100.6 102.7 105.5

86.2 103.0 98.1 106.5

90.7 100.9 95.4 114.5