1. Notes 5.1 Measures of Central Tendency A measure of central tendency is a single number that is used to represent a set of data. Measures of central tendency help you describe a data set and interpret it. The mean, or average, is the sum of a set of numbers divided by how many numbers are in the set. The mode is the number that occurs most often in a set.

2. The median is the middle number (or mean of the middle two numbers) of a set that has been written in numerical (rank) order. Examples: Given data: 22, 37, 27, 21, 31, 29 Data in rank order: 21, 22, 27, 29, 31, 37 Mean: sum = 162, 162 / 6 = 27 Median: (27 + 29) / 2 = 28 Mode: There is no mode.

3. The data above shows the ages of students in a seventh grade class. Which measure of central tendency describes the typical age of a student in the class? Any of the three is acceptable, since mode = median = 12, and mean = 12.5.

4. Your scores on a 100-point math test have been 82, 74, 88, 94, and 96. What are the highest and lowest means you could have after another 100-point test? Which score would be the better representative of your performance for the term? For the highest, add 100 to the sum and divide by six; for the lowest add 0 to the sum and also divide by 6. Highest 89, lowest 72.3, the highest would be the better representative.

5. Urlof the day: http://cnx.rice.edu/content/m11061/latest/

6. homework answers 7) $2.45, $2.45, $3.00, $3.15, $3.25, $3.25, $3.25, $4.00, $4.00, $5.00; $3.38; $3.25; $3.25 8) 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5, 5; about 3.5; 4; 4 9) 1, 1, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 6, 6, 7, 8; 4; 4; 3

7. 10) 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 3, 4, 5, 8; 1.5; 1; 0 11) 8.24; 8; 8; the measures of central tendency are all about 8. 14) $39,000; $27,000; $27,000 and $25,000 sample answer: The median or mode because the mean gives the impression that the typical salary is $39,000. 15) The mean would be around $41,457, but the median and mode would not change.

8. 16)C 17) D 18) Sample answer: The median, which is 1.8, is between the mean of 1.9 and the mode of 1,7.