Answer:
[tex]t = 0.875[/tex]
Step-by-step explanation:
Given
Brand A Brand B
[tex]n_ 1= 12[/tex] [tex]n_2 = 12[/tex]
[tex]\bar x_1 = 21.8[/tex] [tex]\bar x_2 = 18.9[/tex]
[tex]\sigma_1 = 8.7[/tex] [tex]\sigma_2 = 7.5[/tex]
Required
Determine the test statistic (t)
This is calculated as:
[tex]t = \frac{\bar x_1 - \bar x_2}{s\sqrt{\frac{1}{n_1} + \frac{1}{n_2}}}[/tex]
Calculate s using:
[tex]s = \sqrt{\frac{(n_1-1)*\sigma_1^2+(n_2-1)*\sigma_2^2}{n_1+n_2-2}}[/tex]
The equation becomes:
[tex]s = \sqrt{\frac{(12-1)*8.7^2+(12-1)*7.5^2}{12+12-2}}[/tex]
[tex]s = \sqrt{\frac{1451.34}{22}}[/tex]
[tex]s = \sqrt{65.97}[/tex]
[tex]s = 8.12[/tex]
So:
[tex]t = \frac{\bar x_1 - \bar x_2}{s\sqrt{\frac{1}{n_1} + \frac{1}{n_2}}}[/tex]
[tex]t = \frac{21.8 - 18.9}{8.12 * \sqrt{\frac{1}{12} + \frac{1}{12}}}[/tex]
[tex]t = \frac{21.8 - 18.9}{8.12 * \sqrt{\frac{1}{6}}}[/tex]
[tex]t = \frac{21.8 - 18.9}{8.12 * 0.408}}[/tex]
[tex]t = \frac{2.9}{3.31296}}[/tex]
[tex]t = 0.875[/tex]
