Hi there
First find the growth rate between 1990 and 1997
The formula is
P=Ae^rt
P 51 million
A 48 million
E constant
R growth rate?
T time 1,997−1,990=7 years
We need to solve for r
R=[log (p/A)÷log (e)]÷t
R=(log(51÷48)÷log(e))÷7
R=0.009
Now find the population in 2017
P=Ae^rt
P ?
A 48 million
R 0.009
T time 2,017−1,990=27 years
So
P=48×e^(0.009×27)
P=61 million
Hope it helps