Haze weather questionnaire

(1) The number of students participating in this survey is: 20÷5%=400 (people).

400× 15%=60 (person),

A: There are 60 people who know better;

(2) The central angle corresponding to part D is: 360× (1-5%-15%-45%) =126;

(3) According to the meaning of the question:

2000× (1-5%-15%-45%) = 700 (person),

A: There are 700 students who don't know the smog weather.