Winn Dixie sells various flavors of individual servings of y

Winn Dixie sells various flavors of individual servings of yogurt, which are noted in the table to the right. Compute the standard error of the proportion for the random sample size of receipts indicating Yoplait yogurt purchases selected from Winn Dixie\'s electronic journal presented below.

219 receipts selected for sample

Yoplait: 21%