Homework SourseConstruct a 90 confidence interval for the mean difference D
Construct a 90% confidence interval for the mean difference D.. (Round intermediate calculations to 4 decimal places and final answer to 2 decimal places.)
Using the confidence interval, test whether the mean difference differs from zero.
| A sample of 31 paired observations generates the following data: |
Solution
Note that
Lower Bound = dbar - z(alpha/2) * s / sqrt(n)
Upper Bound = dbar + z(alpha/2) * s / sqrt(n)
where
X = sample mean = 2
z(alpha/2) = critical z for the confidence interval = 1.644853627
s = sample standard deviation = 2
n = sample size = 31
Thus,
Lower bound = 1.409151135
Upper bound = 2.590848865
Thus, the confidence interval is
(1.41,2.59) [ANSWER, PART A]
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As 0 is not a part of this interval, then:
OPTION 1: The mean difference differs from zero.
