How realistic would it be to drop about 10% body fat in 15 weeks?

I am considering doing a Bikini competition in the end of September. Next week, I hope to start extreme strict diet and working out 6 days a week, intensely. With a routine like this, how likely do you think it would be for me, a 5'8'' 150 girl with about 22% body fat (according to the calculators online, I do have a lot of muscle), to drop to about 12% for the competition?