Answer:
50 million
Explanation:
Suppose the exponential growth formula that show the population after x years is,

Let the population is estimated from 1992,
That is, for x = 0,
y = 39 millions ( given )
From equation (1),

Also, if x = 5, y = 42 millions ( population in 1997 was 42 million )
From equation (1),
,
Thus, the required formula would be,

If x = 17,
The population in 2009 would be,
