Question

In: Statistics and Probability

The EPA wants to know the daily level of pollutant discharge in the manufacturing district in...

The EPA wants to know the daily level of pollutant discharge in the manufacturing district in Pittsburgh for eight weeks (i.e. 56 days). The monitoring equipment reveals that the mean daily discharge per factory (calculated as total areal discharge divided by total areal factories) is 30.2 tons with a standard deviation of 9.1 tons. Construct a confidence interval for the true population mean of pollutant discharge using a 99% level of confidence.

Solutions

Expert Solution

Given :

as the population standard deviation is unknown (not given) , we need to use t-interval .

The confidence interval formula for population mean is ,

We have to find the 99% confidence interval ,

so c = 0.99

Degrees of freedom = n - 1 = 56-1 = 55

df = 55

Using excel function ,   =TINV( , df )

=TINV( 0.01 , 55 )

=2.668

Now plug the values in the formula ,

Therefore a confidence interval for the true population mean of pollutant discharge using a 99% level of confidence is ( 26.9556 , 33.4444 )

orchestra answered 2 years ago
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