Answer:
Brand 1 Brand 2 Difference
37734 35202 2532
45299 41635 3664
36240 35500 740
32100 31950 150
37210 38015 −805
48360 47800 560
38200 37810 390
33500 33215 285
Sum of difference = 2532+ 3664+740+150 −805+ 560 +390 +285 = 7516
Mean = 
Mean = 
a) d= 939.5


=1441.21
b)SD= 1441.21
c)Calculate a 99% two-sided confidence interval on the difference in mean life.
confidence level =99%
significance level =α= 0.01
Degree of freedom = n-1 = 8-1 =7
So, 
Formula for confidence interval 
Substitute the values
confidence interval 
confidence interval
to 
Confidence interval
to 
Answer:
Step-by-step explanation:
- 1 / 3 + - 7/4
-4/12 - 21/12
=-25/12
9a)
4x - 2 + 30 = 68
4x + 28 = 68
4x = 40
x = 10
9b)
y = 180 -68
y= 112
B is the answer to the question.