Exam Review #3

Exam Review:
#3

Measures of center and spread in a data set and a table.

Finding Mean, Median, and Mode from a Table

• If a class is made up of a range of numbers (ex. 0-3 hours), you must find the midpoint in order to eventually calculate the mean

  • Midpoint = (Max + Min)/2 -> (ex. 0+3/2 = 1.5)

• Multiply the midpoint by the frequency

• Find the total for the frequency and your previous calculation

• Divide the total you got from multiplying by the total frequency

Multiple Choice

The first class in a table is from 10 to 26. What is the midpoint?

• 8

• 18

• 13

• 20

Finding Mean, Median, and Mode from a Table

• To find the median

  • Step 1: take the total frequency and divide by 2

  • Step 2: go to the frequency column and begin counting until you reach that number

  • Step 3: Identify the class that number is in

• To find the mode, identify the class with the highest frequency

Multiple Choice

What is the statistical measure that represents the middle value?

• Median

• Standard Deviation

• Mean

• Range

Multiple Choice

What is the mode of this frequency table?

• There is not a mode

• 8

• 9

• Both 8 & 9

Mean, Median, & Mode

• Mean - the sum of all the data divided by the number of data points in the set

• Median - order all the data points from least to greatest and identify the middle number

  • If you have 2 numbers in the middle, add them together and divide by 2

• Mode - the value that shows up the most in the data set

Multiple Choice

When finding the median you ordered the numbers and were left with 12 and 16 as your middle values, what would be your median?

• 12

• 16

• 2

• 14

Measures of Spread: Range, Standard Deviation & Variance

• Range = Max - Min

• Standard Deviation

  • Enter all your data into List 1

  • STAT -> CALC -> 1) 1-VAR STAT -> CALCULATE -> Sx

• Variance = Standard Deviation x Standard Deviation

Multiple Choice

The Variance of a set of data is 25, what is the Standard Deviation?

• 50

• 625

• 12.5

• 5

Fill in the Blanks

Find the standard deviation (Sx) of this set of data (round to 2 decimal places):

15 10 13 15 29 30 13 15 45 11

Box & Whisker Plots

• To do a Box & Whisker Plot, you must find the Five Number Summary (Min, Q1, Med, Q3, Max)

  • Step 1: Enter all values in data set into List 1

  • Step 2: STAT -> CALC -> 1) 1-VAR STAT -> CALCULATE

  • Step 3: Scroll down until you find the five number summary

Match

Find the 5 number summary for the set of data:

15 10 13 15 29 30 13 15 45 11

• Min

• Max

• Median

• Q1

• Q3

10

45

15

13

29

• 10

• 45

• 15

• 13

• 29

Multiple Choice

What statistical technique can be used to analyze data in groups of 25% (Quartiles)?

• Histogram

• Box and whisker plot

• Bar chart

• Line graph