An SRS of 450 high school seniors gained an average of x ¯ ¯ ¯ x¯ = 22 points in
ID: 3219652 • Letter: A
Question
An SRS of 450 high school seniors gained an average of x ¯ ¯ ¯ x¯ = 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.
Find a 95% confidence interval for based on this sample.
Confidence interval ( ± ± 0.01) is between_______ and_________
What is the margin of error ( ± ± 0.01) for 95%? _________
Suppose we had an SRS of just 100 high school seniors.
What would be the margin of error ( ± ± 0.01) for 95% confidence? __________________
PLEASE ANSWER THE QUESTION AS ASKED, PROVIDE FOUR ANSWER, ONE ANSWER TO EACH BLANK SPACE
Explanation / Answer
for std error =std deviation/(n)1/2 where n=450
=2.1213
for 95% CI. z=1.96
henceConfidence interval =xbar -/+z*std error =17.842 ; 26.158
margin of error =z*std error =4.158
for n=100
std error =4.5
hence margin of error =8.820
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