Answer to Question #71090 in Statistics and Probability for Chris

Question

In an experiment with a new tranquilizer, the pulse rates (per
minute) of 12 patients were determined before they were given
the tranquilizer and again 5 minutes later, and their pulse rates
were found to be reduced on the average by 7.2 beats with a
standard deviation of 1.8. At the level of significance 0.05,
do we have significant evidence that the mean pulse reduction
with this tranquilizer is less than 9.0 beats?