Lesson 2.9Describe Data by Mean Absolute Deviation
Set B · Version ASecond form · supported practice
Learning target I can find the mean absolute deviation (MAD) to describe how spread out data is.
Why This Matters The forecast shows the expected high temperatures for a week. The mean high temperature for the week is 79°F. How can you describe the variation in high temperatures over the week?
RememberDescribe Data by Mean Absolute Deviation
Mean Absolute Deviation (MAD). Formula: MAD = (Sum of distances from mean) ÷ (Total count) The mean absolute deviation, or MAD, is the average distance of each value from the mean. It tells you how spread out the data is: a small MAD means the data is close together, and a large MAD means it is spread out.
- 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
Words: Mean Absolute Deviation (Desviación media absoluta)Deviation (Desviación)Absolute Value (Valor absoluto)Spread (Dispersión)Data distribution (Distribución de datos)
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1Circle the letter of the best answer. Show how you know.
Two soccer goalkeepers track goals allowed per game over 6 games. Keeper A: 1, 2, 1, 3, 2, 1 (mean = 1.67, MAD ≈ 0.67). Keeper B: 0, 4, 1, 3, 0, 2 (mean = 1.67, MAD ≈ 1.33). The coach needs to pick a starter for the championship game. What does a smaller MAD tell you?
- AThe values stay closer to the mean — the keeper is more consistent
- BThe keeper allowed fewer goals overall
- CThe keeper played fewer games
- DThe values are all close to zero
Show your work
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2Circle the letter of the best answer. Show how you know.
Find the mean of 10, 14, 8, 12 and 16.
- A10
- B12
- C14
- D60
Put the data in orderWork- 1OrderSmallest to largest.
- 2CountHow many values?
- 3LocateMiddle, or add and divide.
- 4AnswerSay which measure it is.
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3Circle the letter of the best answer. Show how you know.
Four friends have 6, 9, 4 and 5 stickers. If they share them equally, how many does each get?
- A4
- B5
- C6
- D24
Show your work -
4Circle the letter of the best answer. Show how you know.
A student's first three quiz scores are 82, 90 and 86. What score on a fourth quiz gives a mean of 87?
- A86
- B88
- C90
- D92
Put the data in orderWork- 1OrderSmallest to largest.
- 2CountHow many values?
- 3LocateMiddle, or add and divide.
- 4AnswerSay which measure it is.
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5Circle the letter of the best answer. Show how you know.
The mean is called the balance point because…
- Ait is always the middle value in order
- Bthe amounts above it and below it balance out
- Cit is the most common value
- Dit is always the largest value
Show your work -
6Circle the letter of the best answer. Show how you know.
Two soccer goalkeepers track goals allowed per game over 6 games. Keeper A: 1, 2, 1, 3, 2, 1 (mean = 1.67, MAD ≈ 0.67). Keeper B: 0, 4, 1, 3, 0, 2 (mean = 1.67, MAD ≈ 1.33). The coach needs to pick a starter for the championship game. What is each keeper's mean goals allowed per game?
- Aabout 1.67
- B2
- C6
- D10
Show your work
Explain your thinkingPlayer A's MAD is 2.4 points. If Player B's MAD is 7.2 points, what does that tell you about their consistency?
Sentence starter Player A has a ___ MAD, which means their scores are ___ to the mean. Player B has a ___ MAD, which means their scores are ___ from the mean. The more consistent player is ___ because ___.
Lesson 2.9Describe Data by Mean Absolute Deviation
Set B · Version BSecond form · core practice
Learning target I can find the mean absolute deviation (MAD) to describe how spread out data is.
Why This Matters The forecast shows the expected high temperatures for a week. The mean high temperature for the week is 79°F. How can you describe the variation in high temperatures over the week?
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1Write the letter of the matching item on each line.
Each player's points are listed. Match each player's data set to its correct MAD. (Hint: find the mean first, then average the distances.)
- Bench: 8, 10, 12, 14
- Rookie: 4, 4, 4, 4
- Starter: 5, 15, 5, 15
- AMAD = 2 points
- BMAD = 0 points
- CMAD = 5 points
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2Write the name of the correct group on each line.
Coach is sorting players by consistency. Drag each player's MAD into the bucket that describes their scoring.
- Player with MAD = 1 point
- Player with MAD = 0 points
- Player with MAD = 9 points
- Player with MAD = 12 points
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3Circle the letter of the best answer. Show how you know.
Two soccer goalkeepers track goals allowed per game over 6 games. Keeper A: 1, 2, 1, 3, 2, 1 (mean = 1.67, MAD ≈ 0.67). Keeper B: 0, 4, 1, 3, 0, 2 (mean = 1.67, MAD ≈ 1.33). The coach needs to pick a starter for the championship game. Which keeper should the coach start, and why?
- AKeeper B, because two shutouts is best
- BEither one, because the means are equal
- CKeeper A, because the smaller MAD (0.67) means more consistent performance
- DKeeper B, because a larger MAD means more skill
Show your work -
4Circle the letter of the best answer. Show how you know.
A guard scored 2, 4, 6, 8 points in four scrimmages, so the mean is 5 points. The distances from the mean are 3, 1, 1, 3. What is the mean absolute deviation (MAD)?
- A1
- B2
- C5
- D8
Put the data in orderWork -
5Circle the letter of the best answer. Show how you know.
Two shooters average 11 points a game. Shooter A's MAD is 2 points and Shooter B's MAD is 6 points. Which shooter is MORE consistent?
- AShooter B, because a bigger MAD means a bigger average
- BThey are equally consistent because they have the same mean
- CShooter A, because a smaller MAD means scores stay closer to the average
- DYou cannot tell consistency from MAD
Show your work
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6Find the mistake. Explain it, then show the correct work.
Level 2 Extension — The Deviations That Vanished
- 1Data setA center's rebounds: 3, 7, 11, 15, 19
- 2Find the meanSum = 55, Count = 5, Mean = 55 ÷ 5 = 11
- 3Find each deviation (value − mean)−8, −4, 0, 4, 8
- 4Find the MADMAD = (−8 + −4 + 0 + 4 + 8) ÷ 5 = 0 ÷ 5 = 0
Which step has the mistake? Explain what went wrong, then show the correct work.
Correct workCorrect answer: