Question

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

Answer 1

Answer:

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.