English is not my primary languages and especially english maths are hard for me to grasp. That's why i am asking you to demonstrate, using the actual numbers for Ruby and Perl, what calculations should be performed to gain the numbers your site is showing.
Also, in addition, after reading your link, the situation seems even worse. Using the median Perl outperforms Ruby by ~15%, but the main site does not reflect that at all.
The table you don't understand shows the median but you seem to be calculating the arithmetic mean.