Question 61857
After T years, the value of a car purchased for $20,000 is 
v=20,000(.75)^T 
When will this car be worth $500.00?
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500=20000(0.75)^T
1/40 = 0.75^T
Take the log of both sides to get:
 -1.60206=T(-0.1249387366)
T=12.82 years.
Cheers,
Stan H.