The lengths of the products produced in a production process are controlled. The standard deviation is 0.45 mm. A quality control specialist keeps checking on 40 random units every morning. The average length in one day is 35.62 mm. when; Which of the following is the confidence interval for the population mean at the 95% confidence level? a) P( 23.34 < µ < 24.15 ) = 0.95 B) P( 39.48 < µ < 45.78 ) = 0.95 NS) P( 25.51 < µ < 25.76 ) = 0.95 D) P( 35.48 < µ < 35.76 ) = 0.05 TO) P( 35.48 < µ < 35.76 ) = 0.95
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The lengths of the products produced in a production process are controlled. The standard deviation is 0.45 mm. A quality control specialist keeps checking on 40 random units every morning. The average length in one day is 35.62 mm. when; Which of the following is the confidence interval for the population mean at the 95% confidence level?
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Obtain the 95% confidence interval for the population mean.
The 95% confidence interval for the population mean is obtained below as follows:
Use EXCEL Procedure for finding the critical value of z.
Follow the instruction to obtain the critical value of z:
- Open EXCEL
- Go to Formula bar.
- In formula bar enter the function as“=NORMINV”
- Enter the probability as 0.975
- Enter the mean as 0 and the Standard deviation as 1.
- Click enter
EXCEL output:
From the EXCEL output, the critical value of z at the 95% confidence level is 1.96.
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