A study compared the individual pre-tax yearly income earned by residents from t
ID: 3266038 • Letter: A
Question
A study compared the individual pre-tax yearly income earned by residents from two states. The following table lists the statistics resulting from this study:
A part of the study involved calculating the upper and lower bound of the 95% confidence interval of the mean difference (State A - State B) between the income earned by individuals from the two states. For the purposes of this study, the simplified forumla for the number of degrees of freedom in the appropriate t-distribution will be used. Calculate the confidence interval. Give your answers to 2 decimal places. You may find this Student's t distribution table useful.
a)Lower bound =
b)Upper bound =
Yearly Income Location Sample Size Sample Mean ($'000s) Sample Standard Deviation ($'000s) State A 51 78 18 State B 54 90 39Explanation / Answer
From following resutls
Lower=-23.87
upper= -0.13
Two-Sample T-Test and CI
Sample N Mean StDev SE Mean
1 51 78.0 18.0 2.5
2 54 90.0 39.0 5.3
Difference = (1) - (2)
Estimate for difference: -12.00
95% CI for difference: (-23.87, -0.13)
T-Test of difference = 0 (vs ): T-Value = -2.00 P-Value = 0.048 DF = 103
Both use Pooled StDev = 30.6583
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