What is the mean square velocity of motion of gas molecules, which occupies a volume of 2.5 m ^ 3

What is the mean square velocity of motion of gas molecules, which occupies a volume of 2.5 m ^ 3 at a pressure of 4 * 10 ^ 5 Pa and have a mass of 3 kg?

Given:
m = 3 kg
V = 2.5 m ^ 3
p = 4 * 10 ^ 5 Pa
Find: v -?
Decision:
p = 1/3 * ρ (density) * v ^ 2
p = v ^ 2 * (m / 3V)
v ^ 2 = 3pV / m
v ^ 2 = 3 * 4 * 10 ^ 5 Pa * 2.5 m ^ 3/3 kg
v ^ 2 = 1,000,000
v = 1000 m / s
Answer: v = 1000 m / s