Download Statistics Cheat Sheet

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