Fix comment in students_t_two_samples.cpp.

Fix buggy reasoning in students_t_examples.qbk

[SVN r39578]

doc/distributions/students_t_examples.qbk

@@ -665,10 +665,11 @@ section 1.3.5.3] of the __handbook.
 So with a probability that the difference is due to chance of just
 5.273e-030, we can safely conclude that there is indeed a difference.
 
-The tests on the alternative hypothesis show that the Sample 1 Mean is
+The tests on the alternative hypothesis show that we must
+also reject the hypothesis that Sample 1 Mean is
 greater than that for Sample 2: in this case Sample 1 represents the 
-miles per gallon for US cars, and Sample 2 the miles per gallon for 
-Japanese cars, so we conclude that Japanese cars are on average more
+miles per gallon for Japanese cars, and Sample 2 the miles per gallon for 
+US cars, so we conclude that Japanese cars are on average more
 fuel efficient.
 
 Now that we have the simple case out of the way, let's look for a moment

example/students_t_two_samples.cpp

@@ -189,10 +189,10 @@ void two_samples_t_test_unequal_sd(
 int main()
 {
    //
-   // Run tests for Heat Flow Meter data
-   // see http://www.itl.nist.gov/div898/handbook/eda/section4/eda428.htm
-   // The data was collected while calibrating a heat flow meter
-   // against a known value.
+   // Run tests for Car Mileage sample data
+   // http://www.itl.nist.gov/div898/handbook/eda/section3/eda3531.htm
+   // from the NIST website http://www.itl.nist.gov.  The data compares
+   // miles per gallon of US cars with miles per gallon of Japanese cars.
    //
    two_samples_t_test_equal_sd(20.14458, 6.414700, 249, 30.48101, 6.107710, 79, 0.05);
    two_samples_t_test_unequal_sd(20.14458, 6.414700, 249, 30.48101, 6.107710, 79, 0.05);