This calculator tests whether or not a sample proportion is significantly different than a hypothesized proportion.

To conduct the test, simply fill in the values below and then click the “Calculate” button.

Z-statistic: **-0.30861**

Two-tailed P-value: **0.75762**

**Explanation:**

The formula to find the Z-statistic of the test is as follows:

Z-statistic = (p – p

_{null}) / √[ p_{null}(1-p_{null})/n ]where

*p*is the sample proportion*p*is the null hypothesis proportion_{null}*n*is the sample size

Based on the numbers entered above, the Z-statistic is calculated as:

Z-statistic = (.28 – .30) / √[ .30(1-.30)/50) ] =

**-0.30861**