We have to add 1 in numerator and -10 in denominator because
The difference is 1 in numerator so we add 1 and the difference is -10 in denominator so we subtract -10.
Answer:
Explained below.
Step-by-step explanation:
(1)
The confidence level is, 91%.
Compute the value of α as follows:
(2)
As the population standard deviation is provided, i.e. <em>σ</em> = 256 psi, the <em>z</em> value would be appropriate.
The <em>z</em> value for α = 0.09 is,
<em>z</em> = 1.69
(3)
Compute the 91% confidence interval as follows:
(4)
The 91% confidence interval for population mean implies that there is a 0.91 probability that the true value of the mean is included in the interval, (2942.29, 3057.71) psi.