Why RMS speed is taken in the derivation of kinetic gas equation?

Explanation

Velocity is a vector quantity. The molecules of a gas will move randomly in all possible directions, in one direction. IF the velocity is taken as+ve, in the opposite direction it is-ve. Then sometimes the average velocity may become zero. To avoid this, all the velocities are squared, their mean in calculated and square root is taken for it. Then it will be the true average velocity and it is called RMS velocity.