:1.  Twenty-five independent experiments of the length of a
tube have an SD of .02 inches.  If a 26th measurement were made,
it would be off the exact value of the length of the tube by

 a.  .0008 inches or so
 b.  .10 inches or so
 c.  .02 inches or so
 d.  .004 inches or so
 e.  .50 inches or so