A physicist examines 23 sedimentary samples for mercury concentration. The mean mercury concentration for the sample data is 0.036 cc/cubic meter with a standard deviation of 0.012. Determine the 80% confidence interval for the population mean mercury concentration. Assume the population is approximately normal. Step 1 of 2: Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

The 80% confidence interval is  

Step-by-step explanation:

From the question we are told that

  The sample size is  n = 23

  The sample mean is  

   The standard deviation is  

From the question we are told the confidence level is  80% , hence the level of significance is    

=>  

Generally from the normal distribution table the critical value  of   is  

Generally the margin of error is mathematically represented as  

=>    

Generally 80% confidence interval is mathematically represented as  

=>