I have two letters from two of my science proferssor. I also have a great letter from the coordinator of a national scholarship which I received a year ago in community college [He has PHD in math, and has been the president of the college for three years]. 
I have also asked my sociology teach to write a letter for me. She is nice, and actually very close to me, but she keeps on postponing it which makes me angry. I have asked her to write the letter for me TWO weeks ago, and reminded her twice, but there is NO NEWS!!! She is supposed to submit it online, and I can see that she has not done that so far.
Do you guys think that having a letter from a non-science professor is necessary, considering that I have already three good letters?
 
Thank you
	
		
			
		
		
	
				
			I have also asked my sociology teach to write a letter for me. She is nice, and actually very close to me, but she keeps on postponing it which makes me angry. I have asked her to write the letter for me TWO weeks ago, and reminded her twice, but there is NO NEWS!!! She is supposed to submit it online, and I can see that she has not done that so far.
Do you guys think that having a letter from a non-science professor is necessary, considering that I have already three good letters?
Thank you