Answer:
Step-by-step explanation:
The data is incorrect. The correct data is:
Deluxe standard
39 27
39 28
45 35
38 30
40 30
39 34
35 29
Solution:
Deluxe standard difference
39 27 12
39 28 11
45 35 10
38 30 8
40 30 10
39 34 5
35 29 6
a) The mean difference between the selling prices of both models is
xd = (12 + 11 + 10 + 8 + 10 + 5 + 6)/7 = 8.86
Standard deviation = √(summation(x - mean)²/n
n = 7
Summation(x - mean)² = (12 - 8.86)^2 + (11 - 8.86)^2 + (10 - 8.86)^2 + (8 - 8.86)^2 + (10 - 8.86)^2 + (5 - 8.86)^2 + (6 - 8.86)^2 = 40.8572
Standard deviation = √(40.8572/7
sd = 2.42
For the null hypothesis
H0: μd = 10
For the alternative hypothesis
H1: μd ≠ 10
This is a two tailed test.
The distribution is a students t. Therefore, degree of freedom, df = n - 1 = 7 - 1 = 6
2) The formula for determining the test statistic is
t = (xd - μd)/(sd/√n)
t = (8.86 - 10)/(2.42/√7)
t = - 1.25
We would determine the probability value by using the t test calculator.
p = 0.26
Since alpha, 0.05 < than the p value, 0.26, then we would fail to reject the null hypothesis.
b) Confidence interval is expressed as
Mean difference ± margin of error
Mean difference = 8.86
Margin of error = z × s/√n
z is the test score for the 95% confidence level and it is determined from the t distribution table.
df = 7 - 1 = 6
From the table, test score = 2.447
Margin of error = 2.447 × 2.42/√7 = 2.24
Confidence interval is 8.86 ± 2.24
