Co-Authored By:

##### Asked by: Shu Passinho

personal finance home financing# How do you find the 95 confidence interval on a TI 84?

**Therefore, a z-**interval can be used to

**calculate**the

**confidence interval**.

- Step 1: Go to the z-
**interval**on the**calculator**. Press [STAT]->Calc->7. - Step 2: Highlight STATS. Since we have statistics for the sample already calculated, we will highlight STATS at the top.
- Step 3: Enter Data.
- Step 4:
**Calculate**and interpret.

Accordingly, how do you find the 95 confidence interval?

- Because you want a 95% confidence interval, your z*-value is 1.96.
- Suppose you take a random sample of 100 fingerlings and determine that the average length is 7.5 inches; assume the population standard deviation is 2.3 inches.
- Multiply 1.96 times 2.3 divided by the square root of 100 (which is 10).

**How to Find a Sample Size Given a Confidence Interval and Width (unknown population standard deviation)**

- z
_{a}_{/}_{2}: Divide the confidence interval by two, and look that area up in the z-table: .95 / 2 = 0.475. - E (margin of error): Divide the given width by 2. 6% / 2.
- : use the given percentage. 41% = 0.41.
- : subtract. from 1.

Similarly, it is asked, what is a statistically significant sample size?

Generally, the rule of thumb is that the larger the **sample size**, the more **statistically significant** it is—meaning there's less of a chance that your results happened by coincidence.

For a population with unknown mean and known standard deviation , a **confidence interval** for the population mean, based on a simple random sample (SRS) of size n, is + z^{*} , where z^{*} is the upper (1-C)/2 critical value for the standard normal distribution.