Mary Ellen invests $4000 in an account that earns 1.8% annual interest compounded monthly.

How many years will it take for the balance of this account to reach $6000?

Round your answer to the nearest tenth of a year.

22.5 years to the nearest tenth.

Step-by-step explanation:

The equation is

6000 = 4000 (1 + 0.018/12) ^12t where t = the number of years

(1 + 0.018/12) ^12t = 1.5

1.0015^12t = 1.5

Taking logs:

12t log 1.0015 = log 1.5

12t = log 1.5 / log 1.0015

12t = 270.51

t = 22.54 years.