| Tech is a lot easier to get into than similar quality engineering schools, eg, Cornell, CMU, Northwestern, etc. The acceptance rate is around 60% IIRC, although there is certainly a lot of self selection in the applicant pool so that is a bit deceptive, but it still isn't as competitive to get into as its quality of education would suggest(which isn't necessarily a bad thing, good education for more students).
One or two more ecs that you participated in for 3+ years would certainly help although thats impossible to get now. But I still think you'll probably get in. Is your 3.9 gpa weighted or unweighted? If the latter I'd be surprised if you didn't get in. If the former, you still definitely have a good shot. | 
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