2. (8 points) Zombies are coming, and Fire Dragon Grass is responsible for defense:
First-stage Fire Dragon Grass always spits red flames;
Second-stage Fire Dragon Grass spits red flames half the time and blue flames the other half;
Third-stage Fire Dragon Grass always spits blue flames.
If the attack power of the second-stage Fire Dragon Grass is twice that of the first-stage Fire Dragon Grass, then the attack power of the third-stage Fire Dragon Grass is \qquad times that of the first-stage Fire Dragon Grass.