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3.3 Mean, Median, Mode, Formulas
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3.3 Mean, Median, Mode, Formulas

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Review of Mean, Median, and Mode, as well as the Rate Formula and Perimeter Formula.

Review of Mean, Median, and Mode, as well as the Rate Formula and Perimeter Formula.

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  • 1. Remember the 3 Ms? Mean, Median, and Mode ~Central Tendency~ Section 3.3 September 30, 2008 By Ms. D-H
  • 2. Mean?
    • Mean: the sum of the data items divided by the number of data items.
    • These are data items:
    • 2, 3, 4, 5, 8, 8, and 12
    • 2 + 3 + 4 + 5 + 8 + 8 + 12
    • 7 (total data items)
    • 42 / 7 = the mean, which is 6
  • 3. Median?
    • Odd Number of Data Items : the middle number when the data items are put in numerical order.
    • Even Number of Data Items : the two middle numbers when data items are put in numerical order.
    • Median is the middle of the road
  • 4. Median?
    • So find the median with these data items.
    • 2, 3, 4, 5, 8, 8, and 12
    • They’re in order
    • There are 7 numbers, meaning odd.
    • So which is the middle most number?
    • The median is 5.
  • 5. Mode?
    • Mode: is the data item that occurs most often .
    • There can be one mode , multiple modes , or no mode . You can say how many modes there are too!
    • What about our previous data set?
    • 2, 3, 4, 5, 8, 8, and 12
    • 8 is a mode for these data items.
  • 6. Find me the M, M & Ms
    • 12, 14, 26, 37, 8, and 14
    • Re-order: 8, 12, 14, 14, 26, 37.
    • Mean: 18.5
    • Median: 14
    • How many Modes: 1
    • Mode: 14
  • 7. Find me the M, M & Ms
    • 2.3, 4.3, 3.2, 2.9, 2.7, and 2.3.
    • Re-order: 2.3, 2.3, 2.7, 2.9, 3.2, 4.3.
    • Mean: 2.95
    • Median: 2.8
    • How many Modes? 1
    • Mode: 2.3
  • 8. Find me ONLY Mode:
    • Grape, grape, banana, nectarine, strawberry, strawberry, strawberry, orange, watermelon.
    • How many modes?
    • Just one: strawberry.
  • 9. How many modes?
    • 11, 9, 7, 7, 8, 8, 13, 11
    • 3 Modes
    • 38.5, 55.4, 45.3, 38.5, 68.4
    • 1 Mode
  • 10. Outlier
    • Outlier: is a data item (data value) that is much higher or lower than the other data values.
    • Outliers can affect the mean of a group of data.
    • Example: 2, 3.5, 1, 2.5, 5 billion.
    • Example: 35, 45, 40, 37, -6.
  • 11. Describing Data with M, M, & M.
    • You can use what you know about Mean, Median, and Mode to describe data.
    • But figuring out which M describes it best is difficult.
    I think mode describes it best! Nah! Its got to be mean!
  • 12. Which M, M, & M is best?
    • The favorite movie of students in the eighth grade class?
    • Mode: good for non-numerical data items and for frequent occurrences.
  • 13. Which M, M, & M is best?
    • The distances students in your class travel to school.
    • Median: one student may live much further than everyone else. When an outlier may significantly influence the mean, we use median.
  • 14. Which M, M, & M is best?
    • The daily high temperature during a week in July.
    • Mean: since daily temp. are not likely to have outlier, mean is best. When data have no outlier, use mean.
  • 15. Measures and Central Tendency
    • Your text book is going to ask you determine which MEASURE of CENTRAL TENDENCY best describe the data.
    • Its just asking you to figure out which M works with the data best!
  • 16. Using Formulas Section 3.4 Just two formulas.
  • 17. Substituting into Formulas
    • Formula is an equation that shows a relationship between quantities that are represented by variables.
    • Like: Susie has b books. b is the number of books Susie has. b stands for something.
  • 18. Rate
    • Distance = rate • (time)
    • d = rt
    • Cause remember? r and t next to each other means you multiply them.
    • So…rate multiplied by time = distance.
  • 19. Obvious Example: d = r • t
    • Suppose Ms. Dewey-Hoffman traveled 162 miles in 2 hours. Use the formula.
    • How fast was I going? What was my rate?
    • d = r • t
    • d = distance, or 162 miles.
    • t = time, or 2 hours.
    • 162 miles = r • 2 hours.
  • 20. Obvious Example: d = r • t
    • Suppose Ms. Dewey-Hoffman traveled 162 miles in 2 hours. Use the formula.
    • What was my rate?
    • 162 miles = r • 2 hours .
    • 2 hours 2 hours
    • 162  2 = 82 miles/hour
    • So, Ms. Dewey-Hoffman was traveling at 82 miles/hour to go 162 miles in 2 hours. 82 mph is my r or rate. =]
  • 21. Try These: d = r • t
    • d = 200 yards, t = 24 seconds
    • What don’t we know? Set up equation. Solve.
    • r = 30 feet/minute, t = 5 minutes
    • What don’t we know? Set up equation. Solve.
  • 22. Perimeter Formula: P = 2 l + 2 w .
    • Perimeter = 2(length) + 2(width).
    W W L L
    • The formula simplifies how the perimeter of a rectangle works.
    • Perimeter = l + l + w + w …so…
    • Perimeter = 2 l + 2 w
  • 23. Try These: Tell Me Perimeter
    • Remember: P = 2l + 2w
    • Length = 16.8cm, Width = 27.3cm
    • Length = 8.6cm, Width = 17.4cm
    W L
  • 24. Assignment #16
    • Pages: 134-135: # 5-8 All, 15-18 All.
    • Pages: 139-140: # 5–21 Odd.
    • Make sure you answer ALL parts of each problem, the first set of problems ask for a lot.

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