Class fan slogan

( 1)45%>30%; Use this circle to represent the population, and area C represents 45% of the population; There are 50 people in our class; 50×30%= 15 (person); A: Area B represents about 15 people. (3)9×( 1-45%-30%), =9×25%, =2.25 (ha); A: Area A covers an area of about 2.25 hectares. (4) 60 ÷ (45%-30%) = 60 ÷ 5% =1200 (person); Answer: There are 1200 students in the whole school, so the answer is: c, 15, 2.25, 1200.