solving sets problems using Venn diagram?

Question

find the number of female students who are prefect or who wear spectacles or who are prefects and wear spectacles?

Answer 1

The number of female students who wear spectacles constitute set A and those that are female prefects constitute set B, shown as two circles. The intersection of A and B shows those female students who wear spectacles and are prefects. The intersection is the region where the circles overlap. The union of A and B can be shown as a third circle  C enclosing A and B, so C represents female students that are prefects and wear spectacles.