6th grade · Math · Unit 14 of 17
Center & Spread
Mean, median, range and IQR
What your child practices
Telling a statistical question from a regular question, and describing data with the mean, median, range and interquartile range.
Alabama Course of Study content standard: 6.22; 6.23 · telling statistical questions apart and finding measures of center and variability
How we explain it
Children can open this short lesson before they practice.
- Mean: add the values and divide by how many there are.
- Median: the middle value in order. Range: greatest − least.
- IQR: Q3 − Q1, the spread of the middle half.
Example: What is the mean of 4, 7, 9 and 12? 4 + 7 + 9 + 12 = 32. 32 ÷ 4 = 8. Answer: 8
Center & Spread in Alabama
In the Alabama Course of Study, this is unit 14 of 17 in 6th grade Math, after Dividing Fractions and before Four Quadrants.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
What is the interquartile range (IQR) of 29, 24, 40, 29, 20, 24, 24, 8?
- 22
- 32
- 10
- 7
- 29
7
Hint: Order the data. Q1 = 22 (middle of the lower half), Q3 = 29 (middle of the upper half). IQR = Q3 − Q1.
Question 2
Which is a statistical question?
- How many students are in Room 12?
- How many minutes does it take students at my school to get to school?
- How tall is the school flagpole?
- How many days are in a leap year?
How many minutes does it take students at my school to get to school?
Hint: A statistical question expects answers that vary, so you collect data to answer it.
Question 3
The data 18, 19, 19, 19, 20, 97 has one very large value. Which measure describes the typical value best?
- The range
- The median
- The mean
The median
Hint: One extreme value pulls the mean and range a long way, but the median barely moves.
Question 4
What is the mean of 3, 11, 13, 13, 15?
- 12
- 11
- 13
- 9
- 8
11
Hint: Add them (55) and divide by 5.
Question 5
What is the range of 35, 12, 40, 40, 22, 22?
- 28
- 40
- 29
- 31
- 28.5
28
Hint: Range = greatest − least.
Question 6
What is the median of 22, 6, 5, 11, 21?
- 11.5
- 10
- 11
- 12
- 5
11
Hint: Put the numbers in order. The median is the middle one (or the mean of the two middle ones).