2. 1/2 Let the yard radius be r and the great circle be 2r; Then a small circle with C =2πr and a great circle with C = 4π r; C small circle /C big circle = 1/2

3. There is something wrong with the title, which should be "... more than in April 15", listed as: 15/75=20%.

4. For these two questions, remember the law: (1) First, calculate how much is missing. This question is missing: 280-224=56 (person).

(2) Divide more or less numbers by the corresponding number after the word "than". The question should be: 280.

(3) Calculation result: 56/280=20%.

(4) The same method: Question 2: 56/224=25%

5. Same as the fourth question: (1) B is greater than A: 20.

(2) Divide 20 by "A" after the word "Bi", and A = 100-20=80, that is, 20/80=25%.

6. The proportion of female employees is:1-45% = 55%; There are 30 people here, which is equivalent to more men than women.

That is 55%-45% =10%; Then the number of employees in the whole factory is: 30/ 10%=300 (people).