Choosing the best measure of center (mean or median) means you must already be able to find a mean (add ÷ count), find a median (order, take the middle), and spot a number that is way bigger or smaller than the rest. Warm up those feeders first.
Answer these 3, then press Show my path. No grade — this just points you to the right level.
1. What is the mean of 2, 4, 6? (Add, then divide by 3.)
2. What is the median of 3, 9, 5? (Order first.)
3. In the list 4, 5, 6, 40, which value is far bigger than the rest?
The mean and median both describe the center of data. But one very high or very low value (an outlier) pulls the mean toward it, while the median barely moves. Knowing both lets you pick the fairer one.
Your quick check picks one for you, but you can switch any time:
Level 0 Small steps: find a mean and a middle.
A. Add the list: 2 + 2 + 2 = ___
2 + 2 + 2 = 6.
B. Total is 6, there are 3 numbers. Mean = 6 ÷ 3 = ___
6 ÷ 3 = 2.
C. Order least to greatest: 5, 1, 3. The middle is ___
Ordered: 1, 3, 5. Middle = 3.
Level 1 Find both center measures.
A. Find the mean of 4, 4, 7: add, then divide by 3.
4 + 4 + 7 = 15, and 15 ÷ 3 = 5.
B. Find the median of 8, 2, 6: order, then take the middle.
Ordered: 2, 6, 8. Middle = 6.
C. In 3, 4, 5, 30, which value is the outlier (far from the rest)?
30 is much bigger than 3, 4, and 5 — that's the outlier.
Level 2 See how an outlier moves the mean.
A. Find the mean of 2, 4, 6, 8: add, then divide by 4.
2 + 4 + 6 + 8 = 20, and 20 ÷ 4 = 5.
B. Find the median of 2, 4, 6, 8: order, then average the two middle numbers (4 and 6).
The two middle values are 4 and 6; (4 + 6) ÷ 2 = 5.
1. What is the mean of 1, 5, 9? (Add, then divide by 3.)
1 + 5 + 9 = 15, and 15 ÷ 3 = 5.
2. In the list 6, 7, 8, 50, which value is an outlier?
50 is far larger than 6, 7, and 8.
You've practiced exactly what Lesson 8-4 uses. Time to dive in.
Start Lesson 8-4 →