Question 1051026
The SAT math scores for all seniors in a high school are normally distributed
 with population standard deviation of 200. 
n = 100,  x̄ = 650
(a)
Find a 95% confidence interval estimate of The mean SAT math score for HS seniors

Population SD Known:  will use a z score analysis:
 z = invNorm((1-.95)/2) = invNorm(.05)
critical value equal to z = 1.96

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(b )
ME ={{{ z*sigma/sqrt(n)}}}
ME = 1.96(200/10) = 39.2
650 ± 39.2
We are 95% confident that the mean SAT math score for the seniors is:
between 614.8 and 689.2
Check Arithmetic
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(c) Is a 90% confidence interval estimate of the mean SAT math score wider 
than the 95% confidence interval estimate you got from part (b)? NO
Why? 90% confidence interval z = 1.645 (which is <1.96 Multiplying by smaller number)
Less accuracy, smaller interval