The population of a region is growing exponentially. There were $35$ million people in $1980($when $t=0)$ and $70$ million people in $1990.$ Find an expc for the population $($in millions of people$)$ at any time $t,$ in years after $1980.$

$($Note: if you use decimal approximations for the numerical constants in your work, be sure to retain enough significant figures through your work to subsequent answers are correct.$)$

$P(t)=$

What population do you predict for the year $2000?$

Predicted population in the year $2000$ million people.

What is the doubling time?

Doubling time $=$ years.