data one;
  input density weight;
  cards;
1    37.9
1    40.1
1    37.1
1    38.9
2    37.9
2    33.9
2    34.1
2    43.6
3    35.1
3    30.7
3    33.9
3    33.8
4    30.8
4    28.9
4    25.3
4    30.2
5    17.5
5    21.9
5    18.2
5    18.0
;

proc plot;
  plot weight*density;
run;