Question

A math teacher gets a starting salary of $30,000. IF she gets a 1.5% increase in salary each year, what will her total income be over a thirty year period?
This was a past mathlete problem.
I know we have to use an exponential function, but do I have to use the base e? Or should I just do a base of 1.015?

Answer 1

No it is not base e.  It is 1.015.

An increase of 1.5 % =  1.015 

Year            1,             2,                       3,.........................., 30.
               30000, 3000(1.015),  30000(1.015)²,........... 30000(1.015)²⁹

Her Total Income is sum over the thirty 30 year period:

Sn =  a(r^n  - 1) / (r - 1);                a = 30000,  r = 1.015,  n = 30

Sn =  30000 ( 1.015^30  -  1) / (1.015 - 1)

      =  30000 (1.56308022 - 1) / (0.015) =  1126160.44

Total =  $ 1 126 160.44