Ronaldo is standing by the edge of a circular lake at point A (shown below). He has to get directly to the other side at point B. Instead of walking around the lake from A to B, he decides that he would rather swim. How far must he swim from A to B if the circumference of the lake is 4.71 miles

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?