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QMS 102 (49)
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Department
Quantitative Methods
Course
QMS 102
Professor
Changping Wang
Semester
Winter

Description
Business Statistics I Dr. Changping Wang Example 4.  Consider the following frequency distributions of the test scores for two different sections. Score # of students in Sec #1 # of students in Sec #2 40 and under 50 14 5 50 and under 60 30 13 60 and under 70 60 27 70 and under 80 45 25 80 and under 90 31 20 90 and under 100 20 10 Note that there is a large difference in the number of students in the two sections. So  it is difficult to compare the test score distribution by looking at the frequencies. We need to set up a relative frequency or percentage distribution for two sets of test  scores. Relative Frequency of a class • Portion or percentage of the data that falls in a particular class. • The relative frequency, rf, is given by rf =n, where f is the class frequency  and n is the sample size. Example 5.  For the following frequency distribution, construct a relative  frequency distribution. Session 3 Page 1 Business Statistics I Dr. Changping Wang # Minutes they spent   # of Subscribers 0 and under 10 2 10 and under 20 5 20 and under 30 7 30 and under 40 11 40 and under 50 7 50 and under 60 9 60 and under 70 3 70 and under 80 4 80 and under 90 2 Session 3 Page 2 Business Statistics I Dr. Changping Wang Session 3 Page 3 Business Statistics I Dr. Changping Wang Example 6  : The following table summarizes the number of minutes 50  Internet subscribers spent on the Internet during their most recent  session.  # Minutes they spent # of Subscribers rf 0 and under 10 2 0.04 10 and under 20 5 0.10 20 and under 30 7 0.14 30 and under 40 11 0.22 40 and under 50 7 0.14 50 and under 60 9 0.18 60 and under 70 3 0.06 70 and under 80 4 0.08 80 and under 90 2 0.04 Total 50 1.00 Question: How many subscribers in percentage spent less than 57  minutes on the Internet? Session 3 Page 4 Business Statistics I Dr. Changping Wang Session 3 Page 5 Business Statistics I Dr. Changping Wang Steps for constructing an Ogive Session 3 Page 6 Business Statistics I Dr. Changping Wang Example 6 (continued) Constructing a Cumulative Frequency Distribution and  Draw an OGIVE. The following table summarizes the number of minutes 50 Internet  subscribers spent on the Internet during their most recent session.  # Minutes they spent # of Subscribers rf 0 and under 10 2 0.04 10 and under 20 5 0.10 20 and under 30 7 0.14 30 and under 40 11 0.22 40 and under 50 7 0.14 50 and under 60 9 0.18 60 and under 70 3 0.06 70 and under 80 4 0.08 80 and under 90 2 0.04 Total 50 1.00 Construct a cumulative frequency distribution. Session 3 Page 7 Business Statistics I Dr. Changping Wang EXAMPLE 7  The following Ogive was constructed based on all 30,000 students’ GPAs in  the University of Oakwind. Question 1. The University of Oakwind will give a $2,500 award to any student whose GPA is  3.0 or higher.  What is the percentage of the students who have received this award? a) 80% b) 90% c) 20% d) 10% e) None of the above Question 2. The University of Oakwind will give a $500 award to any student whose GPA is in  the range [2.0, 2.4) (i.e., at least 2.0 but less than 2.4).  How many students will receive this  award? a) 1,000 b) 2,000 c) 3,000 d) cannot be determined e) None of the above Session 3 Page 8 Business Statistics I Dr. Changping Wang Chapter 4 – Numerical Descriptive Measures 4.1. Descriptive Statistics I­Measures of Central Tendency  I) Arithmetic Mean (Average) Session 3 Page 9 Business Statistics I Dr. Changping Wang Example 1.  Session 3 Page 10 Business Statistics I Dr. Changping Wang II) Weighted Mean Session 3 Page 11 Business Statistics I Dr. Changping Wang Example 2.  The salaries of all the employees in the outlets in the city where  you live can be summarized in the following table:  Job classification          # of employees    Annual Salary ($000’s) Senior Management                 3                                  52 Middle Management               10                                 38 Cooking staff                             45                                 20 Serving staff                               74                                 18 Maintenance staff                     7                                  23 What’s the mean annual salary? Session 3 Page 12 Business Statistics I Dr. Changping Wang Example 3.   You are taking a class in which your grade is determ
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