Question

A meteorologist was interested in the average speed of a thunderstorm in his area. He sampled 13 thunderstorms and found that the average speed at which they traveled across the area was 15 miles per hour with a sample standard deviation of 1.7 miles per hour.

Assuming the speed of a thunderstorm is approximately normal, construct a 99% confidence interval for the true average speed of a thunderstorm in his area.

Question

How would I enter this into a TI84 calculator?

Answer 1

Given that, sample size (n) = 13

sample mean = 15 miles per hour

sample standard deviation (s) = 1.7 miles per hour

Using TI-83 calculator we get, the 99% confidence interval for the true average speed of a thunderstorm in his area is,

(13.56, 16.44)

Step 1) Press STAT key and go to TESTS option

Step 2) Then go to TInterval and fill the values as follows:

: 15

S_{​​​​​​X} : 1.7

n : 14

C-Level : 0.99

Then go to Calculate and press ENTER key.

Note: I have used TI-83 plus calculator bu the procedure is same in TI-84 calculator.