Expert: Sherman D. - 4/24/2008

Question
I'm having a brain cramp trying to solve the following problem:

Supplemental inflation-adjusted accounting records have spread among publicly traded companies according to P(t) = 1/ (1 + e(3.1 – 0.2t)), where P(t) is the percentage of firms offering this information and t is measured in years since 1970. During which year did 50 percent of the publicly traded firms provide inflation-adjusted accounts.

can you help. Thanks!

Answer
(1/2) = 1/(1 + e^(3.1 - .2t))
(1 + e^(3.1 - .2t))/2 = 1
1 + e^(3.1 - .2t) = 2
e^(3.1 - .2t) = 1
3.1 - .2t = 10
-.2t = 6.9
t = -34.5

i used the decimal form of 50%, i don't know if that was what i was suppose to do.

anyway, this means that 34.5 years ago was when they provided 50%.

so i would say between 1935 and 1936

other than that, check with answers.yahoo.com to be sure.