Answer: 8329 millions.
Step-by-step explanation:
The exponential growth equation is modeled as :
[tex]f(x)=A(1+r)^x[/tex], where A is the initial amount, r is rate of increase and x is the time period.
Given: The number of computers used in 1980= 18.9 million
The rate of growth = 19% =0.19
The number of years from 1980 to 2015= 35
Now, the number of computers in use in 2015 is given by :-
[tex]f(35)=18.9(1+0.19)^{35}\\\\\Rightarrow\ f(35)=8329.24147329\approx8329[/tex]
Hence, the number of computers in use in 2015= 8329 millions.