by Federico S, Josh M, Jake B, and Layeth K
Examples of Situations with Logs
-exponential growth and decay:
r=rate (as a decimal, not a percentage)
n=quantity of time in which interest is compounded
-ln=log base e
The Studebaker will have a value of $34,373.84 by 2011.
Josh invests $3000 that he earned by selling Edward, his pet albino snake. If his account gives 2% interest, compounded quarterly, how many years will it take him to earn at least $4000.
4t=log (base 1.005) of (4/3)
4t= (log 4/3)/(log 1.005)
t=14.42 (round it up)
It will take 15 years for Josh to earn at least $4000.
Uranium 235 has a half-life of 2700 years. If the original amount of uranium was 60 grams, how many years will it take for 1.875 grams to remain?
(t/2700)=log (base 1/2) of (1.875/60)
The uranium 235 will take 13,500 years to decrease to 1.875 grams.