The ArithmeticMean(s) command returns the arithmetic mean of the byte values of the characters present in the string s. The mean is computed as a floating-point number in hardware precision and is returned as a Maple float.

The arithmetic mean of a sufficiently long random string should be close to $128$.

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$m≔\mathrm{ArithmeticMean}\left(''cat''\right)$

$m≔104.$

$\mathrm{Char}\left(\mathrm{round}\left(m\right)\right)$

$''h''$

$\mathrm{ArithmeticMean}\left(\mathrm{Random}\left(1000000\right)\right)$

$128.004748000000006$