Paragraph 1
A good introductory paragraph. This summarizes the next couple of paragraphs and also has a certain intriguing appeal - it arouses the reader's curiosity and impels him to read further. The first sentence, however, could easily have been dropped - the second sentence would make a more compelling introduction to the essay.
Paragraph 2
Here the writer develops on the thread of diversity. Note that there is an emphasis on aspects that are important to an MBA course (strong analytical skills, math skills, work experience). The writer shows effectively that she has not been 'wasting her time' - besides earning a degree, she has earned valuable work experience and done something for the environment. Volunteer work is a strong advantage while applying to an MBA course - universities love people with a social conscience! (To a lesser degree, this is true if you're applying to other graduate courses as well, as long as you show that your primary interest, now and in the future, is in the field you are applying to). At the same time, it is important that this experience appears genuine - so before making tall claims, make sure that you can substantiate them, preferably by actually doing some volunteer / social work.
The last sentence ties the paragraph together. The argument 'my experiences have shaped me' is invaluable IF you have strong or unusual life experiences and in some cases can also partially compensate for an average or below-average academic record.
Paragraph 3
We come to a shift in focus with this paragraph. The writer wraps up the 'diversity' thread well. Saying that she has a diversity of experience to offer, 'among other things', is a good idea - it implies that there is much more to her, qualities and assets that could not be described here because of space limitations
It might have been a better idea to begin the next topic - 'most important achievement' in a new paragraph. The abrupt change of subject has a slightly