2.9 · Part II
Second Practice Form · Independent Application and Spiral Review
Mean Absolute Deviation · Deviation
- Calculate the mean of the data set
- Find the distance (absolute difference |value − mean|) for each data point
- Average the distances: Add all distances and divide by the count
- Mean Absolute Deviation (Desviación media absoluta) — The average distance of data values from the mean; it describes spread.
- Deviation (Desviación) — How far a number is from the mean.
- Absolute Value (Valor absoluto) — How far a number is from zero. It is never negative.
- Spread (Dispersión) — How far apart the numbers are.
- Data distribution (Distribución de datos) — How the data looks: where it sits and how spread out it is.
- Variability (Variabilidad) — How spread out the numbers are.
- A common mistake in Mean Absolute Deviation is adding the signed deviations (value − mean) instead of their absolute values, so the positives and negatives cancel out to 0. For 6, 8, 10, 12 (mean = 9), the deviations are −3, −1, 1, 3 — they sum to 0, but that is NOT the MAD. Before averaging, take the absolute value of every deviation so each becomes a positive distance: |−3| = 3, |−1| = 1, |1| = 1, |3| = 3. Sum = 8, so MAD = 8 ÷ 4 = 2. A MAD of exactly 0 is a warning sign — it only happens if every value in the data set equals the mean.
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1 MULTIPLE CHOICE
(Lesson 2.3) Find the mean of: 10, 14, 8, 12, 16
- A12
- B14
- C10
- D60
Put the data in orderWork -
2 MULTIPLE CHOICE
(Lesson 2.3) Find the median of: 3, 7, 2, 9, 5
- A5
- B3
- C7
- D5.2
Put the data in orderWork -
3 MULTIPLE CHOICE
(Lesson 2.1) A coach asks: "How many hours does each athlete on the track team sleep the night before a meet?" Why is this a statistical question?
- ABecause the answers will vary from athlete to athlete
- BBecause it is about sports
- CBecause it has a numerical answer
- DBecause the coach asked it
✏️ Workspace & Solution Steps -
4 MULTIPLE CHOICE
The mean of a data set is 15. One value is 11. What is the absolute deviation of that value from the mean?
- A4
- B−4
- C26
- D11
✏️ Workspace & Solution Steps -
5 MULTIPLE CHOICE
A data set has absolute deviations of 3, 1, 5, 2, 4. What is the MAD?
- A3
- B5
- C15
- D1
✏️ Workspace & Solution Steps -
6 MULTIPLE CHOICE
The mean of a data set is 20. A value is 26. What is the absolute deviation?
- A6
- B−6
- C46
- D26
✏️ Workspace & Solution Steps
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7 OPEN RESPONSE
Two basketball teams both average 75 points per game. Team A's last 5 scores: 73, 76, 74, 77, 75. Team B's last 5 scores: 60, 90, 65, 85, 75. Calculate the MAD for each team and explain which team a coach would prefer if they need predictable scoring.
✏️ Mathematical Justification & Response
Writing Task: Justify why your mathematical solution is accurate and complete.