4) It is generally assumed that heart rates is normally distributed. Suppose the standard deviation of heartbeats (in beats per minute) of the general population is 20 bpm. A random sample of 40 individuals leading high-stress lives has a sample variance of 200 (bpm). Test the claim at a 1% level of significance that there is a reduction in heart rate variability for those leading high-stress lives. [Do a complete set-up of the test! Include hypotheses, picture of distribution, etc]