The r.m.s. speed of the molecules of a gas is defined as the square root of the mean of the squared velocities of the molecules of gas. No, r.m.s. speed is different from the average speed.
\(c=v_{rms}=\sqrt\frac{v_1^2+v_2^2+v_3^2}{3}\)
and \(v_{avg}=\frac{v_1+v_2+v_3}{3}\)
