Understanding and application of circle: 1. The circumference of the circular flower bed is 62.8 meters. What is its area? 2. Cut a square piece of paper with a circumference of 24 decimeters into the largest circle. What is the circumference and area of a circle? Application problem: 1. There are 720 students in Xisanletai Central Primary School, including 65438 in Grade 6+0/4 in the whole school, 5/24 in Grade 7, 7/24 in Grade 8, and how many in Grade 9? 2. There are 18 people in our class who have participated in the Olympic Mathematics class, accounting for13 of the whole class, accounting for 2/9 of the whole class. How many students have participated in the Olympic math class? 3. Dongfeng Machine Tool Works produced 400 machine tools in April, an increase of 1/5 in May compared with April. How many machine tools did it produce in May? 4. Arbor Day, planting 180 trees in the fourth grade is 3/5 of that in the fifth grade and 2/3 of that in the sixth grade. How many trees were planted in the sixth grade? The shop brought some fruits and 20 baskets of apples. The number of baskets of pears is 3/4 of that of apples and 3/5 of that of oranges. How many baskets of oranges did you bring? 6. A book has 300 pages. In the first week, I read 1/3 of the whole book. In the second week, the number of pages I read was 4/5 that of the first week. How many pages did I read in the second week?