Recently, I came across situation to calculate the sum, min, max of particular field using awk.
Below is the snippet I've used to calculate the field values.
awk 'BEGIN{
                FS=OFS=",";
                max = -999999999; min = 9999999999;
                print "----------------------------"
        }
        {
                sub(" Total requests: ","",$2);
                val = int($2);
                lines+=1;sum+=val;
                if( val > max ) max = val;
                if ( val < min ) min = val;
        }
        END{
                 print "| Total No of Lines: "lines " Sum: " sum " Average: " sum/lines " Max: " max " Min: " min 
        }' with_out.txt
Text File Contents for parsing:
09/Sep/2008:03:57:09, Total requests: 36, New requests: 34
09/Sep/2008:03:57:10, Total requests: 61, New requests: 58
09/Sep/2008:03:57:11, Total requests: 40, New requests: 38
09/Sep/2008:03:57:12, Total requests: 101, New requests: 97
09/Sep/2008:03:57:13, Total requests: 33, New requests: 35