Salt-free diets are often prescribed to people with high blood pressure. The following data values were obtained from an experiment designed to estimate the reduction in diastolic blood pressure as a result of consuming a salt-free diet for 2 weeks. Assume diastolic readings to be normally distributed.
| Before |
109 |
88 |
91 |
102 |
91 |
94 |
108 |
92 |
| After |
99 |
80 |
84 |
97 |
90 |
84 |
103 |
88 |
(a) What is the point estimate for the mean reduction in the diastolic reading after 2 weeks on this diet? (Give your answer correct to one decimal place.)
(b) Find the 90% confidence interval for the mean reduction. (Give your answers correct to two decimal places.)