The sample size which is required in order to estimate the mean per capita income at the 85% level of confidence with an error of at most $0.46 is 866.
Given mean income of $31.3 and standard deviation of $9.4.
We have to calculate the sample size of confidence interval of 85% and at an error of $0.46.
Margin of error is basically the difference between actual values and calculated values.
Mean =$31.3
Standard deviation=$9.4
Confidence level=85%
Margin of error=$0.46
Margin of error=z*σ/[tex]\sqrt{n}[/tex]
0.46=1.44*9.4/[tex]\sqrt{n}[/tex]
[tex]\sqrt{n}[/tex]=1.44*9.4/0.46
[tex]\sqrt{n}[/tex]=29.42
squaring both sides
n=865.53
Round off and we get the following:
n=866.
Hence the sample size needed to estimate the mean per capita income at the 85% level of confidence is 866.
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