size = "Blank";

var hint = 
'Use the non-relativistic Doppler shift equation for light. Remember the velocity is positive for redshifts (longer observed wavelengths), negative for blueshifts (shorter observed wavelengths)!';

function checkme() {
  size = document.velocity.answer.value - 0;

  RightOnFile = './velocity-correct.html';
  TryAgainFile = './velocity-close.html';
  WayWrongFile = './velocity-wrong.html';

  low_good = -570;
  hi_good  = -250;

  if ((size <= hi_good) && (size >= low_good)) {
    location = RightOnFile;
  }
  else if ((size < low_good) || (size > hi_good)) {
    location = WayWrongFile;
  }
}