SOLUTION: A photocopier was purchased for $12500. The value of the machine each year is 85% of its value the preceding year. To the nearest tenth of a year, how long will it take before it

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: A photocopier was purchased for $12500. The value of the machine each year is 85% of its value the preceding year. To the nearest tenth of a year, how long will it take before it       Log On


   



Question 1204596: A photocopier was purchased for $12500. The value of the machine each year is 85% of its value the preceding year.
To the nearest tenth of a year, how long will it take before it is worth only $1500?

Answer by ikleyn(52905) About Me  (Show Source):
You can put this solution on YOUR website!
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A photocopier was purchased for $12500. The value of the machine each year is 85%
of its value the preceding year.
To the nearest tenth of a year, how long will it take before it is worth only $1500?
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A function which describes the value of this item is this exponential function

    V(t) = V%5B0%5D%2A0.85%5Et,


where V(t) is the current value;  V%5B0%5D  is the original value at t= 0;  t is the time in years.


To find "t", we write

    1500 = 12500%2A0.85%5Et.


Then we divide both sides by 12500

    1500%2F12500 = 0.85%5Et

or

    0.12 = 0.85%5Et.


Next, we take logarithm base 10 of both sides

    log(0.12) = t*log(0.85)

and express

    t = log%28%280.12%29%29%2Flog%28%280.85%29%29 = 13.0463  years.


You may round it to 13.0 years, as requested.     ANSWER

Solved.

It is a standard procedure for solving such problems.

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To see many other similar  (and different)  solved problems,  look into the lesson
    - Problems on appreciated/depreciated values
in this site.

Learn the subject from there.