Deep-brain stimulation has been reported to provide relief from

Deep-brain stimulation has been reported to provide relief from depression.

Deep brain stimulation (DBS) is a neurosurgical procedure used for the treatment of many diseases such as Parkinson's disease, essential tremor, epilepsy, obsessive–compulsive disorder, dystonia. It includes the placement of a medical device called a neurostimulator which sends electrical impulses, through electrodes, to specific targets in the brain.

It is good method to use for the treatment when disorder cannot be adequately controlled with medications, but it can be risky, e.g. because of the electrode misplacement.

9.9 years

a = p(1 + rt) . . account balance after time t at rate r starting with principal p

3000 = 2500(1 + 0.0202t) . . filling in the given numbers

1.2 = 1 + 0.0202t . . divide by 2500

0.2 = 0.0202t . . . subtract 1

0.2/0.0202 = t ≈ 9.901

it will take about 9.9 years for the account balance to reach $3000.