## Introductory Statistics 9th Edition

mean = 393500/400 = 983.75 Variance =σ^2 $=(∑m^2 f-([(∑mf)]^2/N))/N-1$ $= \frac{454960000- (393500\div400)}{399}$ $=(454960000-387105625)\div400$ $=170061.1$ Standard deviation$= \sqrt 170061.1 =412.3846$