total=`expr $mPercent / 100 "*" .482 + $fPercent / 100 "*" .518`

$ mPercent='2.72'
$ fPercent='3.14'
$ bc -l <<< $(echo "$mPercent / 100 "*" .482 + $fPercent / 100 "*" .518")
.02937560000000000000

$ mPercent='.123'
$ fPercent='.345'
$ echo "$mPercent / 100 * .482 + $fPercent / 100 * .518" | bc -l
.00237996000000000000

$ rpm -qf $(type -p /usr/bin/expr)
coreutils-8.21-13.fc19.x86_64

$ mPercent='3.27'
$ fPercent='3.27'
$ echo "$mPercent / 100 * .482 + $fPercent / 100 * .518" | bc -l
.03270000000000000000

$ mPercent=3.27
$ fPercent=3.27

$ bc -l <<< "$mPercent / 100 * .482 + $fPercent / 100 * .518"
.03270000000000000000