Question

Refer to the accompanying TI-83/84 Plus calculator display of a 95% confidence interval. The sample display results from using a simple random sample of the amounts of tar (in milligrams) in cigarettes that are all king size, nonfiltered, nonmenthol, and non-light. Express the confidence interval in the format of mean + or - E.
ZInterval

(23.305,25.075)

mean=23.69

n = 30

The confidence interval is __?__ +or-___?___.

Answer 1

Answer:

The confidence interval is $22.805$

Step-by-step explanation:

We have given,

The Z interval (23.305,25.075)  

Mean $\bar{x}=23.69$

Sample n=30

To find : The confidence interval?

Solution :

We know, The confidence interval is in the format of

$\bar{x}-E$

E denotes the margin of error,

$E=\frac{U-L}{2}$

Where, U is the upper limit U=25.075

L is the lower limit L=23.305

$E=\frac{25.075-23.305}{2}$

$E=\frac{1.77}{2}$

$E=0.885$

Substitute the value of E and $\bar{x}$ in the formula,

$23.69-0.885$

$22.805$

Therefore, The confidence interval is $22.805$