Mathematics: Your professor wants to determine if her students today are performing better in statistics than 10 years ago. End of semester grades from a random sample of students enrolled today and one of students enrolled 10 years ago have been obtained: Today 10 Years Ago 82 88 σ 2 112.5 54 n 45 36 The test statistic for the difference between the two population means is . a) –3 b) –1.5 c) –.65 d) –.47

Your professor wants to determine if her students

Ответ:

josebienka

29.01.2022

z = -3

Step-by-step explanation:

If we had two independent samples, the variance is known and n_1 and n_2 are bigger than 30, the test statistic for the difference between the two population means is calculated as:

$z=\frac{x_1-x_2}{\sqrt{\frac{s_1^2}{n_1}+\frac{s_2^2}{n_2} } }$

Where x_1 and x_2 are the means of the samples, s_1^2 and s_2^2 are the variances of the samples and n_1 and n_2 are the size of the sample.

Finally, replacing x_1 by 82, x_2 by 88, s_1^2 by 112.5 , s_2^2 by 54, n_1 by 45 and n_2 by 36, we get that the statistic is equal to:

$z=\frac{82-88}{\sqrt{\frac{112.5}{45}+\frac{54}{36} } }=-3$

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Ответ:

arodriguez395

15.02.2021

Mathematics

y = 0 and y = -3

Step-by-step explanation:

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