Question 1189932
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Given info:
n = 21 = sample size
xbar = 40 = sample mean
s = 19 = sample standard deviation
C = 0.90 = 90% = confidence level


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Use a calculator or table to find the T critical value  based on these inputs
<ul><li>df = degrees of freedom = n-1 = 21-1 = 20</li><li>confidence level = 90%</li></ul>You should find that the T critical value is roughly t = 1.725


The point estimate is the sample mean (40) which estimates the population mean (mu).


The margin of error (MoE) is
MoE = t*s/sqrt(n)
MoE = 1.725*19/sqrt(21)
MoE = 7.15209135248464
MoE = 7.15



Answer: <font color=red> 40 ± 7.15</font>
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