Chapter 24, Problem 24.1TY

To determine

To find: The 95% confidence interval for the mean blood pressure in the population from which the subjects were recruited.

Answer to Problem 24.1TY

Option (c): (111.2, 118.6).

Explanation of Solution

Reason for the correct option:

Software procedure:

Step by step procedure to obtain the confidence interval using the MINITAB software:

• Choose Stat > Basic Statistics > 1-Sample t.
• In Summarized data, enter the sample size as 27 and mean as 114.9.
• In Standard deviation, enter the value as 9.3.
• Check Options, enter Confidence level as 95.0.
• Choose not equal in alternative.
• Click OK in all dialogue boxes.

Output using the MINITAB software is given below:

Thus, the 95% confidence interval for the mean blood pressure in the population from which the subjects were recruited is (111.2, 118.6).

Reason for the incorrect answer:

Option (a), Option (b) and Option (d) are incorrect, because the corresponding confidence intervals cannot be obtained from the formula of the confidence interval for the one-sample t procedures.

Therefore, the correct option is (b).

Statistics Concept Introduction

Introduction:

The formula for the confidence interval is,

$\overline{x}\pm t*\frac{s}{\sqrt{n}}$

Where, $\overline{x}$ is the sample mean, s is the sample standard deviation, n is the sample size and $t*$ is the critical value.