Question

Refer back to the pizza-delivery Try It exercise. The population standard deviation is six minutes and the sample mean delivery time is $36$minutes. Use a sample size of $20$. Find a$95$% confidence interval estimate for the true mean pizza delivery time

Short answer

The interval estimate for the true mean pizza delivery time is ($33.37,38.63$)

Step-by-step solution

Given Information

Given the data that,

standard deviation is six minutes s and the sample mean delivery time is 36 minutes. Use a sample size of 20.

Explanation

$\text{The sample mean is}36\text{minutes, that is,}\overline{x}=36$

$\text{The random sample of}20\text{pizza delivery restaurants, that is,}n=20$

$\text{The standard deviation is}6\text{, that is,}\sigma =6$

Explanation

Now, using the procedures below, compute the confidence interval using a Ti-83 calculator.

Press STAT and use the arrow (?) to TESTS

Now press the arrow $(\downarrow )$to 7: $Z$interval and press enter

Then use the arrow $(\to )$to STATS and press enter

Now press the arrow (?) and enter the inputs as shown below

Now press the arrow (?) to the calculator and press enter. The output is given below,