Answer:
17.98972134
18 years
Explanation:
Using the compound interest formula we can solve for time
[tex]Principal * (1+ r)^{time} = Amount[/tex]
We post our know values
[tex]240,000* (1+ 0.04)^{time} = 486,000[/tex]
And solve for the unknow
[tex](1.04)^{time} =486,000/240,000\\(1.04)^{time} = 2.025[/tex]
Now we have to use log properties to solve for time
[tex]log_{1.04}2.025 = time[/tex]
[tex]\frac{\log 2.025}{\log 1.04} =17.98972134[/tex]
It will take 18 years
