Math 145

1
Math 145

• September 12, 2006

2
Descriptive Statistics

• Measures of Center
• Mean average
• 2.5, 3.2, 3.2, 3.4, 3.6, 3.7, 3.9, 3.9, 4, 4.2,
  4.2
• Median middle value
• Mode most frequent occurring value.
• Practice Highway mileage
• 13,15,16,16,17,19,20,22,23,23,23,24,25,25,26,28,2
  8,28,29,32

3
Descriptive Statistics

• Measures of Spread (dispersion)
• Range max min
• Standard Deviation
• Five-number summary
• Minimum
• 1st quartile Q1
• Median
• 3rd quartile Q3
• Maximum
• Interquartile range.
• ? Box Plot

4
Linear Transformation

• Xnew a bX
• Effect of Linear Transformation
• Multiplying each observation by b multiplies both
  measures of center (mean and median) and measures
  of spread by b.
• Adding the same number a to each observation adds
  a to measures of center and quartiles but does
  not change the spread.

5
Homework
Exercises Sec 2 1.42, 1.45, 1.47, 1.55-1.57,
1.60, 1.62 Sec3 1.78, 1.80, 1.81, 1.82, 1.83,
1.85, 1.87, 1.89, 1.90, 1.93-95, 1.97, 1.110,
1.115
6
Thank you!