1. Chapter 3.1 Data Description

2. Steps for finding the mean of grouped data 1. Make a table with class boundaries, frequency, midpoint and frequency multiplied by midpoint 2. Fill in the column of the table 3. Find the sum of the final column (frequency times midpoint) 4. Divide the sum by the sum of the frequencies (n) to get the mean.

3. Find the mean of grouped data  The data represent the number of miles run during one week for a sample of 20 runners. Find the mean. Class boundaries Frequency, f Midpoint, X m f * X m 5.5-10.51 10.5-15.52 15.5-20.53 20.5-25.55 25.5-30.54 30.5-35.53 35.5-40.52

4. Modal Class  The mode for grouped data is the modal class.  The modal class is the class with the largest frequency. ClassFrequency, f 5.5-10.51 10.5-15.52 15.5-20.53 20.5-25.55 25.5-30.54 30.5-35.53 35.5-40.52

5. Weighted Mean  Sometimes, you must find the mean of a data set in which not all values are equally represented.  For example, suppose three taxis buy gasoline at three different gas stations. Find the average cost of a gallon of gas: Price per gallon Number of gallons purchased Taxi A$3.229 Taxi B$3.538 Taxi C$3.6311

6. GPA  In a standard 4 point scale, A = 4 grade points, B = 3 grade points, C = 2 grade points, and D = 1 grade point CourseCreditsGrade English Composition I 3A Intro to Psychology 3C Biology I4B Physical Education 2D

7. Determine your grade Suppose that grades are determined using the following percentages: Major Assessment – 50%, Minor Assessments – 25%, and Homework – 25% Major Assessments Minor Assessments Homework 8880100 7587100 9465100 8590100 7595 8050 85 100 A student’s grades are as follows: There is one test remaining for the marking period and the students wants to earn at least an 86 in the class. What is the minimum score the student can get on this final test to reach his or her goal?