1. 14-2 Measures of Central Tendency

2. Measures of Central Tendency
Measures of Central Tendency: Measures of averages
Mean
Median
Mode
Arithmetic Mean
𝑥 , adding the values of the set of data and dividing by the number of values of the data

3. Arithmetic Mean
𝑥 , adding the values of the set of data and dividing by the number of values of the data
Median: The middle value of a set of data. (if there are two middle values, find the mean of those two values)
Mode: The value in the data set that occurs most often. There can be more than one (or no) modes. If there are two models, we say the data is bimodal. Mode may not actually show “center” because it can be largest/smallest value

4. Find the mean, median, and mode
3,5,6,7,7,8,9,11,13,15,22,23,25

5. Use a calculator to find the mean, median of…
23,23,24,25,25,26,27,29,30,36,41

6. To find mean with a frequency distribution:
Find total number of data points used
Multiply each class mark by its frequency
Add up total, then divide by total data points

8. Measures of Central Tendency in a Frequency Distribution
Find the mean of the following frequency distribution
Class Limits
Class Marks
Frequency
F(X)
10-12 1
12-14 3
14-16 5
16-18 12
18-20
20-22 4

9. To find median of freq. distribution
1) Find which class the median is located in
2) Find how numbers are below the class, and at the class. Place them on the line.
3) Place lower class and upper class limit on line. Estimate where median would be.
4) Create a proporiton and solve using cross multiplying.

11. Estimate the median

12. Finding missing values
Bob’s exam grades are 64,67,72,and 69. What does he need on list last exam to bring his average to a 70? The White Oak wrestling team has members that weigh in at 150, 167, 145, 143lbs. If a new member joined and made their average 153lbs, how much did that person weight?