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ONE-VARIABLE STATISTICS CHEAT SHEET SHAPE - Left-skewed - Right-skewed - Symmetric (Normal) CENTER - Mean “average” (use for symmetric) - Median “middle number” (use for skewed) - Mode (happens the most) OUTLIERS - < Q1 – 1.5(IQR) - > Q3 + 1.5(IQR) - Outliers affect the “mean” more than “median” SPREAD - Range (max – min) - IQR (Q3 – Q1) - Standard Deviation Types of Variables: Categorical and Quantitative (Remember: Quantitative can be averaged) Five-Number Summary: Minimum, Q1, Median, Q3, Maximum Graphs: Dotplots, Boxplots, Histograms CALCULATOR IMPORTANT TIPS -Make sure to know how to calculate outliers (see above) -Make sure to know that mean means the center and that standard deviation is the spread -Make sure to know how to calculate the best-fit line and how to get to your TABLE (2nd GRAPH). See back page TWO-VARIABLE STATISTICS CHEAT SHEET Joint Frequency: Entries in a two way table Marginal Frequency: Total of rows or columns; represents totals of categories Relative Frequency: Two-Way table values converted to a decimal or percent; joint frequency divided by overall total Conditional Probability: compares joint frequency divided by a marginal frequency To apply a relative frequency to a larger total, multiply the decimal by the total. (Example: If there are 2000 people at the party, how many are women who like to dance? 2000 X 0.32 = 640) LINEAR REGRESSION AND THE CALCULATOR STAT Edit (put in table – x’s in L1 and y’s in L2)) STAT CALC 4: LinReg (ax+b) and if you can remember VARS YVARS ENTER 3x Example: Best fit line: y = 815.42x + 3779.18 with a strong, positive correlation Statistics Practice Problems 1.) The following data set displays the number of student absences from Sanibel High School for a two-week period. 100, 62, 212, 78, 161, 𝒙, 270, 94, 184, 309 The school calculates the average absences for the two-week period and determines the mean is 160 absences a day. The school has lost the data for day 𝒙 and cannot remember how many students were absent on day 𝒙. How many students were absent on day 𝒙? 2.) The table below shows the enrollment of preschool children at a local day care center. Using the best fit line, predict how many students there will be in 2010? Let x = 0 represent 1980. 3.) The salaries of nine teachers in a local high school math department are listed in the table : i) If this data skewed left, skewed right, or symmetrical? ii.) Calculate the upper and lower boundary using the 1.5(IQR) Rule and state if there are any outliers. 4.) $25000 $52000 $28000 $78000 $38000 $22000 $32000 $30000 $32000 5.) Use the table below the answer the following questions: i.) ii.) iii.) What percent of males are overweight? What is the probability of choosing a female who is underweight? Given that the person is male, what are the chances of him being underweight? 6.) I. What is the probability that Madison takes Route A or B? II.) Answer Key 1.) 130 2.) 46chilren 3.) i.) skewed right ii.) lower: -1250, upper: 72750, outlier: 78,000 4.) B or C 5.) i.) 6% ii) 3% iii) 17% 6.) i.) 60% ii.) D