Calculate the area of a circle with a diameter of 8cm.
Show all your work.

Of 400 people at the school carnival, 95% are students and the rest are teachers. a. how many students are at the school carnival? b. if 55% of the students at the school carnival are boys, how many are girls? c. how many teachers are at the school carnival? d. if 35% of the teachers are male and the rest are female, how many female teachers are at the carnival?