1. 0-12 M EASURES OF C ENTER, V ARIATION, AND P OSITION Objective: 1) Find the measures of central tendency, variation, and position.

2. D EFINITIONS Measures of Center or Central Tendency: Measure of what is average. Most common measures are mean, median and mode. Mean: the sum of the values in a data set divided by the total number of values in the set. Median: middle value, or the mean of the two middle values when the data are in numerical order. Mode: The value(s) that appear most often in a set of data

3. E XAMPLE 1: SWIMMING The table shows the number of laps Ekta swam each day. Find the mean, median, and mode.

4. M EASURES OF S PREAD OR V ARIATION : Describes how widely the data values vary. R ANGE : The difference between the greatest and least values in a set of data.

5. E XAMPLE 2: CELL PHONES The number of minutes Sara talked on her phone each day this week is 63, 21, 24, 52, 74, 56, and 38. Find the range of the minutes.

6. Q UARTILES Divides a data set arranged in ascending order into four groups, each containing about ¼ or 25% of the data. The three quartiles, along with minimum and maximum values, are called a five-number summary.

7. E XAMPLE 3: Find the minimum, lower quartile, median, upper quartile, and maximum of the data shown below. 27, 25, 44, 13, 29, 44, 52, 28, 41

8. I NTERQUARTILE R ANGE : Difference between the upper and lower quartiles. O UTLIER : Extremely high or extremely low value when compared with the rest of the values in the set. To check for outliers: look for data values that are beyond the upper or lower quartiles by more than 1.5 times the interquartile range.

9. T RIVIA … 1.A raccoon's hind feet have an unusual ability. What is this? They can rotate. 2. Raccoons will eat just about anything in urban areas that they get their paws on. They'll even eat toothpaste if they find a tube. What planted crop is a particular favorite of the raccoon? Sweet Corn.

10. E XAMPLE 4: TEXT MESSAGES The table shows the number of text messages Tumu received. a) Identify any outliers in the data b) Find the mean and median of the data set with and without the outlier. Describe the effect.

11. H OMEWORK Pages P39-P40: 2 – 10 even, 14, 15, 16