Out of a large number of cars produced by the automaker, the percentage of batteries that will last for more than $8$ years is
- $[ \int^8_0 \frac{\beta^{\alpha}}{\Gamma (\alpha)} e^{-\beta x} x^{\alpha -1} dx ] \times 100\%$
- $[1- \int^8_0 \frac{\beta^{\alpha}}{\Gamma (\alpha)} e^{-\beta x} x^{\alpha -1} dx ] \times 100\%$
- $[ \int^{\infty}_8 \frac{x \beta^{\alpha}}{\Gamma (\alpha)} e^{-\beta x} x^{\alpha -1} dx ] \times 100\%$
- $[ \int^8_0 \frac{x \beta^{\alpha}}{\Gamma (\alpha)} e^{-\beta x} x^{\alpha -1} dx ] \times 100\%$
