Update rulerSigFigs3.pg

Added hints

ProblemLibrary/setCH151_Measurement/rulerSigFigs3.pg

@@ -56,6 +56,7 @@ $image0 = $rulercm[$a];
 $alt0 = $altruler[$a];
 $m0 = InexactValue($measurement[$a], 2, { tolerance => 0.2});
 $m0uncert = $m0->simpleUncertainty;
+$tick0 = $m0uncert*10;
 
 @rulercm2 = ("ruler0.png", "ruler1.png", "ruler2.png", "ruler3.png", "ruler4.png", "ruler5.png", "ruler6.png","ruler7.png","ruler8.png","ruler9.png");
 
@@ -70,7 +71,7 @@ $alt1 = $altruler2[$b];
 $sf1 = $sigfigs[$b];
 $m1 = InexactValue($measurement2[$b], $sf1, { tolerance => 0.03 });
 $m1uncert = $m1->simpleUncertainty;
-
+$tick1 = $m1uncert*10;
 
 ############################################################
 # Body
@@ -90,7 +91,7 @@ a)  [@ image( $image0, width=>516, height=>225,
  extra_html_tags=>"alt='$alt0'"  )@]*
 
 
-The magnesium strip above measures [____]{$m0} +/- [___]{$m0uncert} cm.
+    The magnesium strip above measures [____]{$m0} +/- [___]{$m0uncert} cm.
 
 
 b)  [@ image( $image1, width=>516, height=>225,  
@@ -104,6 +105,13 @@ END_PGML
 ############################################################
 BEGIN_PGML_HINT
 
+What is the quantity measured by the smallest lines on the ruler in these examples? In other words, how far apart are these markings?
+
+        a. [$tick0] cm
+
+        b. [$tick1] cm
+
+This means that the measurement for these devices should be *one digit more precise* than this. This is called the guess digit and this will define the uncertainty for that measurement. 
 
 To review significant figures and measurement, click [@ htmlLink( protect_underbar("https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%3A_Introductory_Chemistry_(Tro)/02%3A_Measurement_and_Problem_Solving/2.03%3A_Significant_Figures_-_Writing_Numbers_to_Reflect_Precision"), protect_underbar("here"), "TARGET='_blank'" ); @]*
 
@@ -129,4 +137,4 @@ END_PGML_SOLUTION
 
 
 
-ENDDOCUMENT();
+ENDDOCUMENT();