The root mean square (RMS), also known as the quadratic mean, is computed by using the following formula:
$\text{RMS = }\sqrt{\frac{\Sigma x^2}{n}}$
Find the RMS speed of a vehicle recorded at different times: $\text{30 km/h, 50 km/h, 70 km/h, 90 km/h}$. How does the result compare to the arithmetic mean?

• A. $\text{RMS = 60 km/h}$, which is equal to the arithmetic mean.
• B. $\text{RMS = 56.75 km/h}$, which is lower than the arithmetic mean.
• C. $\text{RMS = 64.03 km/h}$, which is higher than the arithmetic mean.
• D. $\text{RMS = 70.25 km/h}$, which is higher than the arithmetic mean.

Answer: (C)