To determine how many times longer Jupiter's orbit is compared to Earth's orbit, we need to compare the two orbital distances.
1. Jupiter's orbit is [tex]$3 \times 10^9$[/tex] miles.
2. Earth's orbit is [tex]$6 \times 10^8$[/tex] miles.
We need to find the ratio of Jupiter's orbit to Earth's orbit. This can be done by dividing the distance of Jupiter's orbit by the distance of Earth's orbit:
[tex]\[ \text{Ratio} = \frac{\text{Jupiter's orbit}}{\text{Earth's orbit}} = \frac{3 \times 10^9}{6 \times 10^8} \][/tex]
When we perform the division, we divide both the numerator and the denominator by [tex]$10^8$[/tex] to simplify:
[tex]\[ \text{Ratio} = \frac{3 \times 10^9}{6 \times 10^8} = \frac{3 \times 10}{6} = \frac{30}{6} = 5 \][/tex]
Thus, Jupiter's orbit is 5 times longer than Earth's orbit.
Therefore, the correct answer is:
[tex]\[ \boxed{5} \][/tex]