Question 1200322
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Answer: <font color=red size=4>2.479</font>


Explanation:


At 95% confidence, the z critical value is roughly z = 1.960
Use a calculator with built in stats functions (eg: TI84) or a reference table to determine this value.


Here is one such table
<a href = "https://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf">https://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf</a>
Scroll to the bottom to locate 1.960, which is one cell above the "95% confidence level".


The margin of error formula for the mean is
E = z*sigma/sqrt(n)
where,<ul><li>z = critical value mentioned earlier = 1.960</li><li>sigma = standard deviation = 4</li><li>n = sample size = 10</li></ul>Take note that the mean isn't involved with the margin of error formula.


So,
E = z*sigma/sqrt(n)
E = 1.960*4/sqrt(10)
E = 2.479225685572
E = <font color=red>2.479</font>
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