Over the three years, we've grown by a factor of
[tex]1.148\times 1.064\times 1.017= 1.242237024 [/tex]
The average growth is given by the geometric mean,
[tex]\sqrt[3]{1.148 \times 1.064\times 1.017} = 1.0749827360...[/tex]
Answer: 7.5%
The geometric mean is always smaller than the arithmetic mean:
[tex]\frac 1 3(14.8\% + 6.4\% + 1.7\%)=7.633\%[/tex]