We want to estimate the mean change in score µ in the population of all high sch
ID: 3261759 • Letter: W
Question
We want to estimate the mean change in score µ in the population of all high school seniors. An SRS of 350 high school seniors gained an average of xx¯ = 22 points in their second attempt at the SAT Mathematics exam. Assume that the change in score has a Normal distribution with standard deviation 45.883. Find xx¯, the standard deviation of the mean change x¯ _____ (±±0.001). Using the 68-95-99.7 Rule (Empirical Rule), give a 95% confidence interval for based on this sample. Confidence interval (±±0.001) is between __ and ___
Explanation / Answer
Solution:-
Given, n = 350
Mean x-bar = 22
Standard deviation = 45.883
Find xbar, the standard deviation of the mean change xbar _____ (±0.001).
45.883 / sqrt(350) = 2.4525
Using the 68-95-99.7 Rule (Empirical Rule), give a 95% confidence interval for based on this sample.
Xbar = 22, = 45.883 and n = 1350
X ± {Z*(/sqrt(n))} = 22 ± 1.96 × 2.4525
= [17.1931 , 26.8069]
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