SOLUTION: between the start of 2005 and the end of 2009, the number of Facebook users can be modelled by the exponent equation u=0.43*(3.17)^t, where u is the number of users in millions nd

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: between the start of 2005 and the end of 2009, the number of Facebook users can be modelled by the exponent equation u=0.43*(3.17)^t, where u is the number of users in millions nd       Log On


   



Question 1035108: between the start of 2005 and the end of 2009, the number of Facebook users can be modelled by the exponent equation u=0.43*(3.17)^t, where u is the number of users in millions nd t is the number of years since 2004 (1<=t<6)
How do I find the year in which the exponential model predicts that the number of users would first reach 200 million? (I know that the 1 year since 2004, the number of Facebook users is 1.4 million)
Thanks for your help

Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
If u is the number of Facebook users in millions, and u=.43*(3.17)^t, where t is the number of years since 2004, then:
200=.43*(3.17)^t
465.12=3.17^t
log 465.12=log 3.17^t
log 465.12=t log 3.17
t=log 465.12/log 3.17=5.32385131974 years after 2004 that the amount of Facebook users will reach 200 million. ☺☺☺☺