(a) Test whether u, > H, at the a = 0.01 level of significance for the given sample data. (b) Construct a 99% confidence interval about u,-H2.

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Parts a and b please

(a) Test whether u, > H, at the a = 0.01 level of significance for the given sample data.
(b) Construct a 99% confidence interval about u,-H2.
Transcribed Image Text:(a) Test whether u, > H, at the a = 0.01 level of significance for the given sample data. (b) Construct a 99% confidence interval about u,-H2.
Expert Solution
Step 1

a) 

The provided sample means are shown below:

Xˉ1=48.2\bar X_1 = 48.2

Xˉ2=46.1\bar X_2 = 46.1

Also, the provided sample standard deviations are:

s1=5.5s_1 = 5.5

 s2=11.8s_2 = 11.8

and the sample sizes are n1=20n_1 = 20 and n2=17n_2 = 17

 

Step 2

Null and Alternative Hypotheses

The following null and alternative hypotheses need to be tested:

Ho: μ1\mu_1 = μ2\mu_2

Ha: μ1\mu_1 > μ2\mu_2

This corresponds to a right-tailed test, for which a t-test for two population means, with two independent samples, will be used.

Rejection Region

Based on the information provided, the significance level is α=0.01\alpha = 0.01, and the degrees of freedom are df=35df = 35. In fact, the degrees of freedom are computed as follows, assuming that the population variances are equal:

Hence, it is found that the critical value for this right-tailed test is tc=2.438t_c = 2.438,  for α=0.01\alpha = 0.01 and df=35df = 35

The rejection region for this right-tailed test is .

Test Statistics

Since it is assumed that the population variances are equal, the t-statistic is computed as follows:

t=Xˉ1Xˉ2(n11)s12+(n21)s22n1+n22(1n1+1n2)t = \frac{\bar X_1 - \bar X_2}{\sqrt{ \frac{(n_1-1)s_1^2 + (n_2-1)s_2^2}{n_1+n_2-2}(\frac{1}{n_1}+\frac{1}{n_2}) } }

=48.246.1(201)5.52+(171)11.8220+172(120+117)=0.711 = \frac{ 48.2 - 46.1}{\sqrt{ \frac{(20-1)5.5^2 + (17-1)11.8^2}{ 20+17-2}(\frac{1}{ 20}+\frac{1}{ 17}) } } = 0.711

Decision about the null hypothesis

Since it is observed that t=0.711tc=2.438t = 0.711 \le t_c = 2.438, it is then concluded that the null hypothesis is not rejected.

Using the P-value approach: The p-value is p=0.2408p = 0.2408, and since p=0.24080.01p = 0.2408 \ge 0.01, it is concluded that the null hypothesis is not rejected.

Conclusion

It is concluded that the null hypothesis Ho is not rejected. Therefore, there is not enough evidence to claim that the population mean μ1\mu_1 is greater than μ2\mu_2, at the 0.01 significance level.

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