Question

A study of fox rabies in a country gave the following information about different regions and the occurrence of rabies in each region. A random sample of

n₁ = 16

locations in region I gave the following information about the number of cases of fox rabies near that location.

x₁:

   Region I Data

2	8	8	8	7	8	8	1
3	3	3	2	5	1	4	6

A second random sample of

n₂ = 15

locations in region II gave the following information about the number of cases of fox rabies near that location.

x₂:

   Region II Data

1	1	3	1	6	8	5	4
4	4	2	2	5	6	9

Use a calculator with sample mean and sample standard deviation keys to calculate x₁ and s₁ in region I, and x₂ and s₂ in region II. (Round your answers to two decimal places.)

1. Calculate X1, X2, S1, S2 (round to 2 dec. places)

2. What is the value of the sample test statistic? Compute the corresponding z or t value as appropriate. (Test the difference μ₁ − μ₂. Do not use rounded values. Round your final answer to three decimal places.)

3. Find a 95% confidence interval for μ₁ − μ₂. (Round your answers to two decimal places.)

Upper Limit =

Lower limit =

Answer 1

1)

from above

x1 =4.81

x2=4.07

s1 =2.74

s2 =2.49

2)

std error =√(S21/n1+S22/n2)=		0.939
test stat t =(x1-x2-Δo)/Se =		0.794

3)

Point estimate of differnce =x1-x2     =			0.746
for 95 % CI & 14 df value of t=			2.145
margin of error E=t*std error                   =			2.015
lower bound=mean difference-E     =			-1.27
Upper bound=mean differnce +E      =			2.76