A school psychologist notes that the average number of times that students are disruptive during class is 1.4 [μ=1.4] times per day. Following recent classroom policy changes, the psychologist tests if the number of disruptions during class has changed. He records the following number of disruptions observed during a class day: 2, 4, 3, 5, 1, 1, and 4. A. Test the hypothesis that the number of complaints has increased or decreased using a .05 level of significance.
B. Compute effect size using estimated Cohen's d.

Reject the Null ;

0.928

Step-by-step explanation:

Given the data: 2, 4, 3, 5, 1, 1, 4

Sample mean = (2 + 4 + 3 + 5 + 1 + 1 + 4) / 7 = 2.857

Standard deviation, s = 1.57 ( using calculator)

The hypothesis :

H0 : μ = 1.4

H1 : μ ≠ 1.4

Since sample size is small, use T test

Test statistic :

Tstatistic = (x - μ) / s/sqrt(n)

Tstatistic = (2.857 - 1.4) / 1.57/sqrt(7)

Tstatistic = 1.457 / 0.593 = 2.455

Two tailed test at α = 0.05

Tcritical at df = 7-1 = 6 ; α = 0.05 = 2.447

Tstatistic > Tcritical ; reject the null

Since ;

2.455 > 2.447 ; we reject the null ;

There is significam evidence that Number of complaints has changed.

Effect size ;

d = (x - μ) / s

d = (2.857 - 1.4) / 1.57

d = 1.457 / 1.57

d = 0.928

the correct answer is you spend $55.78 more in a brand store that buy ing in a normal store.

step-by-step explanation:

brand = spend   $ 135.85 total

store = spend $80.07 total

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1