Average Elements of of each key->value

[tgr0ss83]

I have an array that looks like this:

array
      0 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '00:00' (length=5)
          2 => string '34.83' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '00:00' (length=5)
          5 => string '34.83' (length=5)
      1 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '01:00' (length=5)
          2 => string '32.07' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '01:00' (length=5)
          5 => string '32.07' (length=5)
      2 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '02:00' (length=5)
          2 => string '28.69' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '02:00' (length=5)
          5 => string '28.69' (length=5)
      3 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '03:00' (length=5)
          2 => string '28.17' (length=5)
          3 => string '12/08/2011' (length=10)
          4 => string '03:00' (length=5)
          5 => string '28.17' (length=5)

**What I'm trying to do is average each 2/5 element with eachother into > a new array with the Date/Time. so have something like**
------------------------------------------------------------------------

array
0 =>
array
0 => string '12/08/2011' (length=10)
1 => string '00:00' (length=5)
2 => string 'AVERAGE OF 2&5' (length=5)

1 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '01:00' (length=5)
          2 => string 'AVERAGE OF 2&5' (length=5)
      2 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '02:00' (length=5)
          2 => string 'AVERAGE OF 2&5' (length=5)
      3 => 
        array
          0 => string '12/08/2011' (length=10)
          1 => string '03:00' (length=5)
          2 => string 'AVERAGE OF 2&5' (length=5)

Any help would be appreciated

thank you.