SOLUTION: A laptop computer is purchased for $1200 . Each year, its value is 70% of its value the year before. After how many years will the laptop computer be worth $300 or less? Wr

Question 697434: A laptop computer is purchased for $1200 . Each year, its value is 70% of its value the year before. After how many years will the laptop computer be worth $300 or less?

Write the answer as a whole number.
Found 3 solutions by rfer, josmiceli, MathTherapy:
Answer by rfer(16322)   (Show Source): You can put this solution on YOUR website!
1200*0.70=840
840*0.70=588
588*0.70=411.60
411.60*0.70=288.12
Four years
Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
For now, let = the purchase price
The value is:
1st yr:
2nd yr:
3rd yr:
4th yr:
etc
Let = the current value of the laptop
------------------
If the number of years,

( I use the because it makes the
1st year )

Take the log base 10 of both sides

After the 4th year, the laptop will be
worth $300 or less.
----------------
Check answer:

OK

Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!
A laptop computer is purchased for $1200 . Each year, its value is 70% of its value the year before. After how many years will the laptop computer be worth $300 or less?

Let y = year that laptop will be worth $300, or less
Since it loses 70%, or .7 of its value, then:

≈

After approximately 4 years, it will be worth < $300 ($288.12).

You can do the check!!

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