https://www.hackerrank.com/challenges/awk-1/problem
awk '{ if ( $4=="" )  print "Not all scores are available for",$1 }' awk-1.txt

https://www.hackerrank.com/challenges/awk-2/problem
awk '{ if ($2 >=50 && $3 >= 50 && $4 >= 50)  print $1,": Pass"; else print $1,": Fail" }' awk-2.txt

https://www.hackerrank.com/challenges/awk-3/problem
awk '{ total=$3+$4+$2;avg=total/3;if ( avg >= 90 ) grade="A";else if ( avg >= 80) grade ="B";else if (avg >= 70) grade ="C";else grade="FAIL";print $0,":",grade; }' awk-3.txt
awk '{ total=$3+$4+$2;avg=total/3;if ( avg >= 80 ) grade="A";else if ( avg >= 60) grade ="B";else if (avg >= 50) grade ="C";else grade="FAIL";print $0,":",grade; }' awk-3.txt

https://www.hackerrank.com/challenges/awk-4/problem
awk 'ORS=NR%2?";":"\n"' awk-4.txt