## Introductory Statistics 9th Edition

a. Because the frequency given are only for the computers sold at an electric shop, it represents only a sample. b. Mean =$∑fx\div n$ = $486.5/25$=19.46 Variance = =$(∑(fx)^2 - ([(∑fx)]^2/N))/(n-1)$ = $\frac{10524.25-(236682.3\div25)}{24}$ =$(10524.25-9467.29)\div24$ =44.04 Standard deviation = $\sqrt 44.04 = 6.6363$