In

$2017,$

the estimated world population was

$77\mathrm{.}5$

billion. Use a doubling time of

$39$

years to predict the population in

$2031,$

$2069,$

and

$2108.$

Question content area bottom

Part $1$

What will the population be in

$2031?$

The population will be

enter your response here

billion.

$($Round to one decimal place as$$ needed.$)$