Find the probability of three female students standing together. Denominator A77 is all the postures of a ***7 person, numerator A33 is all the postures of three girls, and A55 is the question: Don't you ask three girls to stand together? Take these three girls as a bundle, and add those four boys, it is equivalent to five. In this case, it is A55, and the three girls are regarded as a whole. This is the answer.

Four boys are not adjacent, and the denominator is the same as the first one. This question uses interpolation method, that is, arrange the boys' situations first, whether they are adjacent or not, and let them sit down first, which is A44. Then, if the questions are not adjacent, let the girls sit in the air and you can look at your fingers. Three of the four fingers are empty, so these three girls can sit in these three spaces, which meets the requirements of the topic. They will not be adjacent.