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An engineer wanted to estimate the true mean resistance of a certain electrical circuits (?) by...

An engineer wanted to estimate the true mean resistance of a certain electrical circuits (?) by a sample mean (?̅). It is known that the population is normal, and the population standard deviation is ?=0.25 ohms. Determine the required sample size (?) so that he will be 90% confident of being correct within ± 0.06.

Math   Statistics-And-Probability   
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Answer #1

We have given here,                  
                  
Population standard deviation =0.25  
Margin of error =E=0.06  
Level of significance =   0.1  
Z critical value is (by using Z table)=   1.645  
Sample size formula is                   


=46.98
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