SOLUTION: A laptop computer is purchased for $5000 . Each year, its value is 70% of its value the year before. After how many years will the laptop computer be worth 800 or less? Write th

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: A laptop computer is purchased for $5000 . Each year, its value is 70% of its value the year before. After how many years will the laptop computer be worth 800 or less? Write th      Log On


   

Question 1191512: A laptop computer is purchased for $5000 . Each year, its value is 70% of its value the year before. After how many years will the laptop computer be worth 800 or less?
Write the smallest possible whole number answer.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
P=$5000(0.70)^t, where t is number of years. so if t=0, at the beginning, it is worth $5000, and it is worth $3500 the first year.
800=5000(0.70)^t
divide by 5000
0.16=0.70^t
log (0.16)=t log (0.70)
t=log 0.16/log 0.70=5.14 years
so it will be at 6 or more years