(2) The total number of participants in the model airplane competition is 6.25 = 24.
The car model is 4 6 = 2 3, that is, the central angle is 360× 25 %× 23 = 60.
The central angle of the sector where the empty mode is located is 360-60-360× (25%+25%) =120.
There are 24×120 360 = 24×13 = 8 people.
Complete bar chart: (5 points)
(3) It is estimated that the number of winners participating in the model airplane competition this year is about 32×2400 80 =960, (7 points).
The number of winners participating in the "empty model competition" is about 960× 120 360 =320. (8 points)
So the answer is: 4,6,24, 120.