Question

Heart rate variability (HRV), the measure of the time interval between heart beats is a method for assessing the effects of stress on an athletes's body. Low HRV can indicate fatigue and over training, while HRV is an indication of good health and a high level of fitness. A one minute test is performed at two different times - 8 am and 8 pm- for a professional athlete over a 7 day period. The following statistics were recorded.  

	8 am	8 pm
mean	77.3	61.5
Standard deviation	6.8	8.2

Determine if there is sufficient evidence to indicate that the professional athlete's mean HRV reading is lower in the evening (8 p.m.) than in the morning (8 a.m.). use the critical value approach at 5% level of significance.

Answer 1