3a) $\bar{x} = 15.4375$ $s_0 = 0.2973$ 3b) $80\% = 0.8$ $\alpha = 1 - 0.8 = 0.2 \to P(|Z| \ge \alpha) = P(|Z| \ge 0.2) = 0.8$ $\frac{\alpha}{2} = 0.1 \to P(|Z| \ge 0.1) = 0.4$ Table 2 $\to Z = 1.28$ $P(-Z, \le Z \le Z_0.1) = 0.8$ $P(-1.28 \le \frac{15.4375 - \mu}{0.2973/\sqrt{8}} \le 1.28) = 0.8$ $-1.28 \le \frac{15.4375 - \mu}{0.2973/\sqrt{8}} \le 1.28 (\frac{0.2973}{\sqrt{8}})$ $-0.1345 \le 15.4375 - \mu \le 0.1345$ $0.1345 \le 15.4375 - \mu \le 0.1395$ $15.572 \le \mu \le 15.303$ 3c) t-test comparison confident interval $\bar{x}_1 = 15.4375$ $\bar{x}_2 = 14.6$ $\alpha = 0.2$ $s_1 = 0.2975$ $s_2 = 0.24$ $\frac{\alpha}{2} = 0.1$ $n_1 = 8$ $n_2 = 10$ $t_{cal} = \frac{\bar{x}_1 - \bar{x}_2}{\sqrt{\frac{s_1^2}{n_1} + \frac{s_2^2}{n_2}}} = 2.6479 \approx$ $JF = F = \frac{s_1^2/s_2^2}{(n_1 - 1)/(n_2 - 1)} = 13.324 = 13$ Table 5: $t_{table} = 1.350$ $\therefore t_{cal} > t_{table} \to statistically \ different$
Added by Melissa P.
Close
Step 1
The first part calculates a confidence interval for the mean of the first sample. The second part uses a t-test to compare the means of two samples. Show more…
Show all steps
Your feedback will help us improve your experience
Rashmi Sinha and 91 other Intro Stats / AP Statistics educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Assume that the populations are normally distributed. (a) Test whether $\mu_{1} \neq \mu_{2}$ at the $\alpha=0.05$ level of significance for the given sample data. (b) Construct a $95 \%$ confidence interval about $\mu_{1}-\mu_{2}$. $$ \begin{array}{lcc} & \text { Sample 1 } & \text { Sample 2 } \\ \hline n & 15 & 15 \\ \hline \bar{x} & 15.3 & 14.2 \\ \hline s & 3.2 & 3.5 \\ \hline \end{array} $$
Inferences on Two Samples
Inference about Two Means: Independent Samples
Hypotheses for a statistical test are given, followed by several possible confidence intervals for different samples. In each case, use the confidence interval to state a conclusion of the test for that sample and give the significance level used. Hypotheses: $H_{0}: \mu=15$ vs $H_{a}: \mu \neq 15$ (a) $95 \%$ confidence interval for $\mu: \quad 13.9$ to 16.2 (b) $95 \%$ confidence interval for $\mu: \quad 12.7$ to 14.8 (c) $90 \%$ confidence interval for $\mu: \quad 13.5$ to 16.5
Hypothesis Tests
Making Connections
Independent random samples of 80 measurements were drawn from two quantitative populations, 1 and $2 .$ Here is a summary of the sample data: $$\begin{array}{lcc} & \text { Sample 1 } & \text { Sample 2 } \\\hline \text { Sample Size } & 80 & 80 \\\text { Sample Mean } & 11.6 & 9.7 \\\text { Sample Variance } & 27.9 &38.4\end{array}$$ a. If your research objective is to show that $\mu_{1}$ is larger than $\mu_{2}$, state the alternative and the null hypotheses that you would choose for a statistical test. b. Is the test in part a one- or two-tailed? c. Calculate the test statistic that you would use for the test in part a. Based on your knowledge of the standard normal distribution, is this a likely or unlikely observation, assuming that $H_{0}$ is true and the two population means are the same? d. $p$ -value approach: Find the $p$ -value for the test. Test for a significant difference in the population means at the $1 \%$ significance level. e. Critical value approach: Find the rejection region when $\alpha=.01 .$ Do the data provide sufficient evidence to indicate a difference in the population means?
Large-Sample Test of Hypotheses
A Large-Sample Test of Hypothesis for the Difference between Two Population Means
Recommended Textbooks
Elementary Statistics a Step by Step Approach
The Practice of Statistics for AP
Introductory Statistics
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD