PLEASE HELP ME PLEASE Find the area and the perimeter of the shaded regions below. Give your answer as a completely simplified exact value in terms of a (no approximations). The figures below are based on semicircles or quarter circles and problems b), c), and d) are involving portions of a square ​

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?