(1) According to the meaning of the question: 49÷49%= 100 (person),

So the number of people in Selected Graduates this time is100;

(2) According to the meaning of the question:1-(5%+36%+49%) =10%, 10% × 360 = 36,

Then the degree of the central angle of the sector where Grade C is located in the statistical chart of this sector is 36;

(3) The number of people in C is 100-(49+36+5)= 10 (people), and the bar graph is completed, as shown:

(4) According to the meaning of the question:1500× (49%+36%) =1275 (person),

It is estimated that about 1275 students will reach Grade A and Grade B in this safety knowledge contest.

So the answer is: (2) 36.