What is the main determining factor of the boundary between the layers

Explanation:

The atmospheric boundary layer is defined as the lowest part of the troposphere that is directly influenced by the presence of the earth's surface, and responds to surface forcing within a timescale of about an hour or less.

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.