P(t)=0.8/(1+1.67e^-0.16t)

The model represents the proportion of new computers sold that use windows 98. Let t=0 represent 1998, t=1 represent 1999, and so on.

1)determine the maximum proportion of new computers sold that will use win 98. That is, determine the limit of P(t) as t -> infinity

2)using a graphing utlility graph p(t)

3)When will 75% of new computers sold use win 98?