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You did these with your group. Now do them on your own — the model above is yours to copy.

1. 1

   Same stepsFinish what the group started. Use the model above, step for step.

   Let's try together: New data set: a dog walker earns $9, $11, $16, and $12 over 4 days. First, what is the total? Next, how many values are in the data set? That number is what we divide by. Last, divide the total by 4. Is your answer bigger than the smallest day and smaller than the biggest day? It should be.

   My first step is ___ , because the problem asks for ___ .

   Show your work

You answered these out loud. Now write them.

Answer, then say how you know — the reason is the part that counts.

1. 2

   Think it throughHow many points has Sofia scored in games 1 through 9?

   1. A133 points
   2. B150 points
   3. C135 points
   4. D15 points

   Why is that the answer?

   I chose ___ because ___ .
2. 3

   Think it throughTo finish with a mean of 15 points across 10 games, how many points does Sofia need in all?

   1. A150 points
   2. B133 points
   3. C15 points
   4. D25 points

   How do you know?

   I chose ___ because ___ .
3. 4

   Think it throughHer nine games total 13 points below the target mean and 11 points above it. What must game 10 be for the data to balance at 15?

   1. A17 points — 2 above the target mean
   2. B13 points — 2 below the target mean
   3. C15 points — exactly the target mean
   4. D24 points — enough to double the points above

   Explain your thinking.

   I chose ___ because ___ .
4. 5

   Back to the modelFour games are below 15 and four games are above 15. Does that already mean the data balances at 15? What else would you have to measure?

   Counting games is not enough because ___. To balance, I have to measure how ___ each score is from ___, and then compare the total ___ to the total ___.

Use the words

Fill each blank with a word from the bank.

• The value found by adding all the data and dividing by how many values there are is the ___.
• A common everyday word that means the same thing as the mean is the ___.
• A single number that describes the typical value of a whole data set is a ___.
• The value where the total amount above equals the total amount below is the ___.

Explain the thinking

1. 6

   Find the mistakeAnother student made this exact mistake in this lesson. Explain why it is wrong, then write what they should have done.

   The mistake: The most common mistake with the mean is adding correctly and then dividing by the wrong number — or not dividing at all.
2. 7

   Say moreWe piled all 60 counters together and then redistributed them equally into 4 bins. How is that the same as arithmetic?

   Combining all the counters is the same as ___ the values.
3. 8

   Change one numberGo back to Part 1 and pick one problem you already solved. Change one number in it, then solve your new version. Show every step.

   If ___ changed to ___ , then ___ .

   Show your work

Last check

These two come from Lesson 2.7. If they are shaky, that is the lesson to revisit — not this one.

1. 9

   Show what you knowQuick check — you've got this: Data set: 8, 12, 10, 14. What is the mean?

   1. A11
   2. B44
   3. C12
   4. D10

   Explain your choice.

   I know it is ___ because ___ .
2. 10

   From Lesson 2.7Quick check — you've got this: What is 19.2 ÷ 0.8?

   1. A24
   2. B2.4
   3. C240
   4. D0.24
3. 11

   From Lesson 2.7If each piece were 2.8 feet instead, how many whole pieces could you cut?

   1. A5
   2. B6
   3. C7
   4. D8

Be honest — this tells your teacher what to do next