To calculate the growth rate of GDP from year 1 to year 2, you can use the following formula:
\[ \text{Growth Rate} = \frac{\text{GDP in Year 2} - \text{GDP in Year 1}}{\text{GDP in Year 1}} \times 100 \]
Plugging in the values:
\[ \text{Growth Rate} = \frac{7.5 \text{ billion} - 6 \text{ billion}}{6 \text{ billion}} \times 100 \]
\[ = \frac{1.5 \text{ billion}}{6 \text{ billion}} \times 100 \]
\[ = 0.25 \times 100 \]
\[ = 25% \]
Therefore, the growth rate of GDP from year 1 to year 2 is 25%.