The fasting blood glucose level of a randomly selected person was measured for seven days and the following readings were made: 7.0, 7.7, 6.8, 7.1, 7.1, 6.1, 7.3. It is reasonable to assume the glucose level distribution is normal. A diabetes researcher would like to study the variability in the fasting blood glucose level readings for this person. The researcher believes that fasting blood glucose never varies more than 0.8 mmol/L.
(Round your answers to 4 decimal places)
(a) Test the appropriate hypotheses to determine if the sample data present sufficient evidence to reject the researcher's claim. Use α = 0.05 and the critical value approach.
(b) What is the approximate p-value for the test statistic? Draw your conclusion using α = 0.05.
(c) Estimate the population variance using a 90% confidence interval. Based on this interval, can we infer at the 90% confidence that the population variance is significantly less than 1?