We can display the information given as an equation:
2000 * [tex] r^{19} [/tex] = 4000; r = increase per annum
Now, we rearrange and solve for r:
[tex] r^{19} [/tex] = 2
r = [tex] \sqrt[19]{2} [/tex] = 1.037.....
We can now work out the increase for 5 years like so:
2000 * [tex] r^{5} [/tex] = 2400.205..... ⇒ $2400
