diff --git a/statistics/exercises/correlationsignificance.m b/statistics/exercises/correlationsignificance.m
index 97c09e7..013b8a9 100644
--- a/statistics/exercises/correlationsignificance.m
+++ b/statistics/exercises/correlationsignificance.m
@@ -6,10 +6,12 @@ y = randn(n, 1) + a*x;
 
 %% (b) scatter plot:
 subplot(1, 2, 1);
-plot(x, a*x, 'r', 'linewidth', 4 );
+plot(x, a*x, 'r', 'linewidth', 3 );
 hold on
 %scatter(x, y );   % either scatter ...
-plot(x, y, 'o' );  % ... or plot - same plot.
+plot(x, y, 'o', 'markersize', 2 );  % ... or plot - same plot.
+xlim([-4 4])
+ylim([-4 4])
 xlabel('x')
 ylabel('y')
 hold off
@@ -48,8 +50,9 @@ hold on;
 bar(b, h, 'facecolor', 'b');
 bar(b(b>=rq), h(b>=rq), 'facecolor', 'r');
 plot( [rd rd], [0 4], 'r', 'linewidth', 2 );
-xlabel('correlation coefficient');
-ylabel('probability density of H0');
+xlim([-0.2 0.2])
+xlabel('Correlation coefficient');
+ylabel('Probability density of H0');
 hold off;
 
-savefigpdf( gcf, 'correlationsignificance.pdf', 12, 7 );
+savefigpdf( gcf, 'correlationsignificance.pdf', 12, 6 );
diff --git a/statistics/exercises/correlationsignificance.pdf b/statistics/exercises/correlationsignificance.pdf
new file mode 100644
index 0000000..7607e59
Binary files /dev/null and b/statistics/exercises/correlationsignificance.pdf differ