Question

An advertisement for a popular supermarket chain claims that it has had consistently lower prices than four other full-service supermarkets. As part of a survey conducted by an "independent market basket price-checking company," the average weekly total, based on the prices (in $) of approximately 95 items, is given for two different supermarket chains recorded during 4 consecutive weeks in a particular month.

Week	Advertiser ($)	Competitor ($)
1	254.28	255.93
2	240.67	255.75
3	231.84	255.15
4	234.07	261.21

(a) Is there a significant difference in the average prices for these two different supermarket chains? (Use α = 0.05. Round your answers to three decimal places.)

1-2. Null and alternative hypotheses:

H₀: μ_d = 0 versus H_a: μ_d < 0

H₀: μ_d < 0 versus H_a: μ_d > 0    

H₀: μ_d = 0 versus H_a: μ_d ≠ 0

H₀: μ_d = 0 versus H_a: μ_d > 0

H₀: μ_d ≠ 0 versus H_a: μ_d = 0

3. Test statistic:  t =

4. Rejection region: If the test is one-tailed, enter NONE for the unused region.

t > ______

t < _______

(c) Construct a 99% confidence interval for the difference in the average prices for the two supermarket chains. (Round your answers to two decimal places.)
$  to $  

Answer 1

a)

H₀: μ_d = 0 versus H_a: μ_d ≠ 0

3) test statistic t =-2.978

4) t >3.182

t< -3.182

c)

99% confidence interval for the difference in the average prices= -49.74 , 16.15