# Print a message before starting to read input
BEGIN { print "Enter a list of names and scores: "; print "" }

      # At each line of input, assign array elements
      # NR is current line number, $1 is first field on line, $2 is second ...
      { name[NR] = $1; score[NR] = $2 }

# After input finished (type ctrl-D), print out arrays and calculate average
END { print "" # print a blank line
      for (i = 1; i <= NR ; i = i+1) { # i is array index, NR is n of lines
	  sum = sum + score[i]  # sum is initally zero, like all Awk variables
	  print "Name: " name[i] " Score: " score[i] " Running sum: " sum
	}
	average = sum / NR # NR is total number of lines in file
        print ""
	print "average score " average
     }

Here is a sample program run:

$ awk -f scores
Enter a list of names and scores:

Jack 90
Jill 100
Jane 110
 
Name: Jack Score: 90 Running sum: 90
Name: Jill Score: 100 Running sum: 190
Name: Jane Score: 110 Running sum: 300
 
average score 100