neptune7896在大作中写到: 平均70分的大学成绩，但有较强的工作背景与很好的essay，申请美国top20的MBA有没有希望？...... 

Most schools will review GPA less than 3.0.(excluding berkerly and UCLA, and cambridge) 
However, as far as I know 70/100 means 2.5 more or less. It is really a backoff for you, because in ranking of USNEWS, they evaluate GPAs as one factor. So school who care for USNEWS ranking are reluctant to recruit low GPAs. 

For b-schools, sometimes, a ranking like a stock, they have to make their stocks high even by hurting business. I mean abandon good guys. 

Everybody knows that some cool guys got a shit GPA in bachelor, the same in US. 

Most canadian school have a tough line for GPA. 
A friend told me that such b-schools are not real b-schools, they want to be a b-school, but actually still an academic school. 

for US second tier b-school , the 80% GPA range is about 2.7-3.6 
For third tier, it is 2.5-3.5, you know you still have a big chance. 
But for tops, it is 3.3-4.0 
Anyway, this is a statistics of median 80%.

For some schools, low GPA is fatal, for example, UCLA, UCBerkely, so do not waste fees on them. 
But for some most good school, low GPA is not that terrible. 
And as I know, nothing could balance a lower GPA, just leave it here. 
Try to tell AdCom, that 1. you college gave you no opptunity to choose course. 
Or, Your parents forced you to enter some one major. 
Above two are common explanations Chinese used. 
But, try to apply NON-GPA-Loving schools, this is extremely important. 

I you found a school ranked higher in B-week, but low in USNEWS, then that school must be a careless one on GPA. A general rule for whom want really to learn some practical things in MBA program, ones ranked low in USNEWS but Higher in B-week probably are ideal, cause they are more of a business school rather than an academy. Use the UWNEWS ranking minus B-week ranks, if result is negative, then forcus on it more, this is more likely to be a joke, but may reveal some facts. 

If you want to a an admirable PHD, go to ones like Stanford, if hope to be a money creator, go Warton. 
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Above is my poor opinions. 
Hai, will you apply for next fall, if so, interested in communication more. 

Do not forge fake transcripts.