Question

An analyst is reviewing a dataset of temperatures recorded at airports in the U.S. In a random sample of 87 airports, she finds the average summer temperature to be 87 degrees Fahrenheit. What value of z should be used to calculate a confidence interval with a 95% confidence level?

Answer 1

Answer:

We use z = 1.96

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$.

So it is z with a pvalue of $1-0.025 = 0.975$, so $z = 1.96$

We use z = 1.96