A school organized a student calligraphy competition and evaluated the entries according to four grades: A, B, C and D. Now, the evaluation results of some students' calligraphy works are randomly sel

A school organized a student calligraphy competition and evaluated the entries according to four grades: A, B, C and D. Now, the evaluation results of some students' calligraphy works are randomly selected. Solution: (1) ∵ There are 24 people in grade A, accounting for 20% in the pie chart.

∴ The sample size this time is: 24 ÷ 20% =120;

(2) According to the fact that the proportion of Grade C in the pie chart is 30%,

The number of people in Grade C is: 120×30%=36.

∴ The number of people in Grade D is: 120-36-24-48= 12.

As shown in the figure:

(3) ∵ The proportion of A and B works in the sample is: (24+48) ÷120×100% = 60%.

∴ The school received 750 entries in this activity, and 750×60%=450 entries reached Grade B or above.