The standard error is an estimate of the standard deviation of the sample statistic. There are different formulas we used to solve for the standard error based on the mean or proportion.
For this particular problem, the formula for the standard error is given by
![SE=\sqrt{(p\left(1-p\right))/(n)}](https://img.qammunity.org/2019/formulas/mathematics/college/nio4dy4l8gbqur7oan1qmbbe1kjmabv8b0.png)
where p is the given sample proportion, and n is the sample size.
The value of z is actually not needed in the computation of the standard error.