Questions: Independent random samples from normal populations produced the results shown in the table to the right. Assume that the population variances are equal. Complete parts a through d below.
a. Calculate the pooled estimate of σ².
sᵖ²=0.5731
(Round to four decimal places as needed.)
b. Do the data provide sufficient evidence to indicate that μ₂>μ₁? Test using α=0.10.
What are the null and alternative hypotheses?
A. H₀ · μ₁-μ₂=0.10
B. H₀: μ₁-μ₂=0
Hᵃ: μ₁-μ₂ ≤ 0.10
Hᵃ · μ₁-μ₂<0
C. H₀: μ₁-μ₂=0.10
D.
H₀: μ₁-μ₂=0
Hᵃ: μ₁-μ₂>0
What is the test statistic?
t=
(Round to two decimal places as needed.)
Transcript text: Independent random samples from normal populations produced the results shown in the table to the right. Assume that the population variances are equal. Complete parts a through d below.
a. Calculate the pooled estimate of $\sigma^{2}$.
\[
s_{p}^{2}=0.5731
\]
(Round to four decimal places as needed.)
b. Do the data provide sufficient evidence to indicate that $\mu_{2}>\mu_{1}$ ? Test using $\alpha=0.10$.
What are the null and alternative hypotheses?
A. $H_{0} \cdot \mu_{1}-\mu_{2}=0.10$
B. $H_{0}: \mu_{1}-\mu_{2}=0$
$H_{a}: \mu_{1}-\mu_{2} \leq 0.10$
$H_{a} \cdot \mu_{1}-\mu_{2}<0$
C. $H_{0}: \mu_{1}-\mu_{2}=0.10$
D.
\[
\begin{array}{l}
H_{0}: \mu_{1}-\mu_{2}=0 \\
H_{a}: \mu_{1}-\mu_{2}>0
\end{array}
\]
What is the test statistic?
$\mathrm{t}=$ $\square$
(Round to two decimal places as needed.)
Solution
Solution Steps
Step 1: Calculate the pooled standard deviation (Sp)
Using the formula $S_p = \sqrt{\frac{(n_1-1)S_1^2 + (n_2-1)S_2^2}{n_1 + n_2 - 2}}$, we find $S_p = 0.76$.
Step 2: Compute the t-statistic (t_STAT)
Using the formula $t_{STAT} = \frac{\bar{X}_1 - \bar{X}_2}{S_p\sqrt{\frac{1}{n_1} + \frac{1}{n_2}}}$, we find $t_{STAT} = -2.1$.
Step 3: Determine the degrees of freedom (df)
The degrees of freedom for the test is $df = n_1 + n_2 - 2 = 6$.
Step 4: Find the critical value(s) for the t-distribution
For a significance level of 0.1, the critical value(s) is/are -1.44.
Step 5: Make a decision
Since the computed $t_{STAT}$ is outside the range of the critical value(s), we reject the null hypothesis $H_0$.
Final Answer:
Based on the computed t-statistic and the critical value(s), we reject the null hypothesis $H_0$. This suggests that there is a significant difference between the two sample means at the given significance level.