You used SS₂ = Σ(x-x) when calculating variance and standard deviation. An alternative formula for the standard deviation that is sometimes convenient for hand calculations is shown below. You can find the sample variance by dividing the sum of squares by n-1, and the sample standard deviation by finding the square root of the sample variance. Complete parts (a) and (b) below. (Ex)² SSX = Ex² n Click the icon for a table of the ages (in years) of shoppers at a local store. (a) Use the shortcut formula to calculate the sample standard deviation. S= (Simplify your answer. Round to one decimal place as needed.)

The coefficient of variation CV describes the standard deviation as a percent of the mean. Because it has no units, you can use the coefficient of variation to compare data with different units. Find the coefficient of variation for each sample data set. What can you conclude? Standard deviation CV = • 100% Mean E Click the icon to view the data sets. Data Table C/heights = 5.0 % (Round to the nearest tenth as needed.) Heights Weights CVweights =% (Round to the nearest tenth as needed.) 68 181 77 169 72 167 72 207 71 177 70 175 78 185 69 186 67 221 70 216 67 209 73 206

The variance and the standard deviation are related by the fact that the square root of the variance is equal to the standard deviation. Suppose the variance of the time it takes to complete a bachelor's degree is 0.8. Find the standard deviation. Round your answer to four decimal places.

Find the area of the shaded region. The graph to the right depicts IQ scores of adults, and those scores are normally distributed with a mean of 100 and a standard deviation of 15. Click to view page 1 of the table. Click to view page 2 of the table. 120 The area of the shaded region is - (Round to four decimal places as needed.)