Xihai Metropolis Daily (May 2, 20091) reported: "Xining has reached the stage of creating a sanitary city.

(1) According to the histogram, the number of people who are "poor" in this questionnaire survey is 10, and the number of people who are "poor" in the departmental statistical chart accounts for 5%, so the sample size is10 ÷ 5% = 200;

(2) The average number of people in the fan chart accounts for 1-25%-50%-5%=20%, so the central angle α = 360× 20% = 72;

(3) As the sample size is 200, it can be seen from the histogram that the number of "ordinary" people is 200-50- 100- 10=40, so the histogram can be completed;

(4) Strengthening citizens' awareness of creating a sanitary city is the premise of improving the city appearance and environment.