1. The problem statement, all variables and given/known data Experiment 15.2 (note this is from a book about 5 years old, and the book has no solutions!!!). I am simply unsure how to calculate between parallax with 1% error and parallax with 50% error etc. Please see the scan I done of the page: http://img210.imageshack.us/my.php?image=savevx9.jpghttp://img210.imageshack.us/my.php?image=savevx9.jpg 2. Relevant equations d = 1/p 3. The attempt at a solution I've tried p=1/d = 1/30 (for ground based) although how do I then account for '50%' error etc? With this book not having solutions (or even answers!) I am just getting further confused as I know these should be very simple calculations.