Presentation on theme: "1) Angelique made scores of 85, 56, and 91 on her first three statistic quizzes. What does she need to make on her next quiz to have an 80 average?"— Presentation transcript:
1) Angelique made scores of 85, 56, and 91 on her first three statistic quizzes. What does she need to make on her next quiz to have an 80 average?
2) Mr. Plum’s math class of 25 students had an average of 85 on the Chapter 1 test. Miss Scarlet’s class of 22 students had an average of 89 on the same test. What would the average be of the two classes combined?
3) A teacher recorded 5 test scores for a student one semester: 54, 67, 75, 82, 97. Looking back at her records she realized that the 54 really should be a 45. After making the correction, what would happen to the mean score for this student? What would happen to the median?
Measures of Center Mean - The arithmetic average Use to represent the mean of a sample The mean is not resistant – it is affected by outliers.
Measures of Center Trimmed mean is computed by first ordering the data values from smallest to largest, deleting a selected number of values from each end of the ordered list, and finally averaging the remaining values. The trimming percentage is the percentage of values deleted from each end of the ordered list.
Measures of Center Mode - The number the occurs the most The median is resistant – it is not affected by outliers. - 50th percentile Median - The middle of the data
- 25th percentile Quartile 1 (Q 1 ) - The middle of the first half of the data - 75th percentile Quartile 3 (Q 3 ) - The middle of the second half of the data Interquartile Range (IQR) - Q 3 – Q 1 Work page 91 #3
1) The following are the homeruns Barry Bonds hit each season from 1986 to a)Find the mean and median. b) How did the 73 homeruns he hit in 2001 affect the mean? median?
2) Five 3rd graders, all about 4 feet tall, are standing together when their teacher, who is 6 feet tall joins the group. What happens to the mean height? median height?
3) Last year a small accounting firm paid each of its five clerks $22,000, two junior accountant $50,000 each and the firm’s owner $270,000. What is the mean salary paid to this firm? How many employees ear less than the mean? What is the median salary? How could an unethical recruiter use statistics to mislead prospective employees?
4) Faculty salaries at a college have a median of $32,500 and a mean of $38,700. What does this indicate about the shape of the salary distribution?
5) The mean and median salaries paid to major league baseball players in 1993 were $490,000 and $1,160,000. Which of these number is the mean, and which is the median? Explain.
6) You are responsible for planning the parking needs for a new 256-unit apartment complex and you are told to base the needs on the statistic “the average number of vehicles per household is 1.9”. a) Which average will be helpful to you (mean, median, mode)? b) Explain why 1.9 cannot be the median or mode. c) If the owner wants parking that will accommodate 90% of all the tenants who own vehicles, how many spaces must you plan for?