Question

You may need to use the appropriate appendix table or technology to answer this question.

The following results come from two independent random samples taken of two populations.

Sample 1	Sample 2
n1 = 50	n2 = 25
x1 = 13.6	x2 = 11.6
σ1 = 2.5	σ2 = 3

(a)

What is the point estimate of the difference between the two population means? (Use

x₁ − x₂.)

(b)

Provide a 90% confidence interval for the difference between the two population means. (Use

x₁ − x₂.

Round your answers to two decimal places.)

to

(c)

Provide a 95% confidence interval for the difference between the two population means. (Use

x₁ − x₂.

Round your answers to two decimal places.)

to

Answer 1

	sample 1		sample 2
x1            =	13.600	x2            =	11.600
n1           =	50	n2           =	25
σ1           =	2.500	σ2           =	3.000
std error σ1-2=√(σ21/n1+σ22/n2)    =			0.6964

a)

Point estimate of differnce '=x1-x2 =

2.000

b)

for 90 % CI value of z=			1.645
margin of error E=z*std error =			1.1455
lower bound=(x1-x2)-E =			0.85
Upper bound=(x1-x2)+E =			3.15
from above 90% confidence interval for population mean =(0.85 , 3.15)

c)

for 95 % CI value of z=			1.9600
margin of error E=z*std error =			1.3650
lower bound=(x1-x2)-E =			0.64
Upper bound=(x1-x2)+E =			3.36
from above 95% confidence interval for population mean =(0.64,3.36)