Question

In order to estimate the difference between the average hourly wages of employees of two branches of a department store, the following data have been gathered. Assume the degrees of freedom are 36. (Assume unequal variance)

	Sample 1	Sample 2
	Downtown Store	North Mall Store
n	25	20
xbar	$9	$9
s	$2	$1

Q. What is a point estimate for the difference between the population means?

Q. What is the critical value for a 95% confidence interval for the difference between the two populations means?

Q. What is the margin of error for a 95% confidence interval for the difference between the two population means? (Provide 2 decimals)

Q. What is the 95% confidence interval for the difference between the two populations means?

Lower limit =      (Provide 2 decimals)

Upper limit =      (Provide 2 decimals)

Answer 1

a) point estimate = difference in sample means = x̅1-x̅2 =    9.000   -   9.0000   =   0.0000

b)

Degree of freedom, DF=       36  
t-critical value =    t α/2 =    2.028   (excel formula =t.inv(α/2,df)

c)

std error , SE =    √(s1²/n1+s2²/n2) =    0.458          
margin of error, E = t*SE =    2.028   *   0.458   =   0.93

4)

confidence interval is                   
Interval Lower Limit = (x̅1-x̅2) - E =    0.0000   -   0.929   =   -0.93
Interval Upper Limit = (x̅1-x̅2) + E =    0.0000   -   0.929   =   0.93

please revert for doubt..