1. **State the problem:** We want to find the upper limit of a 90% confidence interval for the mean systolic blood pressure after the program, based on a sample of 28 participants. 2. **Identify the known values:** - Sample mean $\bar{x} = 132$ mmHg - Sample standard deviation $s = 9$ mmHg - Sample size $n = 28$ - Confidence level = 90% 3. **Find the critical $t$-value:** Since the population standard deviation is unknown and the sample size is less than 30, we use the $t$-distribution with degrees of freedom $df = n - 1 = 27$. For a 90% confidence interval, the significance level is $\alpha = 1-0.90 = 0.10$. The upper limit corresponds to the upper bound of the confidence interval: - The $t$-value is $t_{\alpha/2, df} = t_{0.05, 27}$. Using a $t$-table or calculator, $t_{0.05, 27} \approx 1.703$. 4. **Calculate the standard error (SE):** $$ SE = \frac{s}{\sqrt{n}} = \frac{9}{\sqrt{28}} \approx \frac{9}{5.2915} \approx 1.70 $$ 5. **Calculate the upper limit of the confidence interval:** $$ \text{Upper Limit} = \bar{x} + t_{\alpha/2, df} \times SE = 132 + 1.703 \times 1.70 \approx 132 + 2.90 = 134.90 $$ **Final Answer:** The upper limit of the 90% confidence interval for the mean systolic blood pressure is **134.90** mmHg.