Respuesta :

400 / ( 1 + e^(-x)) = 350
1 + e^(-x) = 400/350
1 + e^(-x) = 8/7
e^(-x) = 8/7 - 1
e^(-x) = 1/7
1/e^(x) = 1/7
e^(x) = 7
x = log ( base e ) 7 or:
x = ln 7
x = 1.94591