Question

Exercise 1. Based on the following information:

Population 1	Population 2
n1 = 50	n2= 80
x1 = 355	x2 = 320
population standard deviation 1= 34	population standard deviation 2= 40

1. What is the best point estimate for the difference between two population means (mean 1− mean 2)?
2. Construct a 95% confidence interval estimate for the difference between two population means.

Answer 1

n1 =50 , n2 = 80

= 355 , = 320

= 34 , = 40

1)

best point estimate = ( - ) = ( 355 - 320) = 35

best point estimate = 35

2)

formula for the confidence interval is

Where Zc is the Z critical value for c = 95%

Zc = 1.96

22.13 < μ1​ − μ2 ​< 47.87

Thus we get confidence interval is = (22.13 , 47.87)