Field Notesgrade 7 math
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Solution key: Read the pile of numbers

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Camp · Read the pile of numbers

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1 of 8 · data-c01

Median of 3, 5, 8, 9, 12?

Dot plot of scores. One dot per observation. Values: 3, 5, 8, 9, 12.
  1. Median means the middle of an ordered list.
  2. 3,5,8,9,12 is already ordered with five values.
  1. The third value, 8, has two values on each side, so median = 8.
  2. Check: cross off 3 with 12, then 5 with 9; 8 remains.

Answer: 8

2 of 8 · data-c02

Median of 4, 6, 10, 14?

  1. Four ordered values leave two middle positions.
  2. In 4,6,10,14, those values are 6 and 10.
  1. Average them: (6+10)÷2=16÷2=8.
  2. Check: 8 is halfway between 6 and 10, two units from each.

Answer: 8

3 of 8 · data-c03

Range of 2, 5, 7, 11, 15?

  1. Range is the distance from the smallest to largest value.
  2. Smallest = 2 and largest = 15.
  1. Range = largest − smallest = 15−2=13.
  2. Check: 2+13=15, spanning the whole list.

Answer: 13

4 of 8 · data-c04

A box plot has Q1 = 4 and Q3 = 11. What is the IQR?

  1. The interquartile range (IQR) is the width of the box in a box plot. Its ends are the lower quartile, Q1, and upper quartile, Q3. Subtract Q1 from Q3.
  2. The supplied quartiles are Q1=4 and Q3=11.
  1. IQR = Q3−Q1 = 11−4=7.
  2. Check: 4+7=11. The minimum and maximum are used for range instead.

Answer: 7

5 of 8 · data-c05

A circle graph is divided into 24 equal-sized slices. Six slices are blue. What percent of the circle is blue?

  1. Percent means a fraction written out of 100.
  2. Blue / total slices = 6/24 = 1/4.
  1. One fourth of 100 is 25, so blue is 25%.
  2. Check: 0.25 × 24 = 6, the number of blue slices.

Answer: 25 %

6 of 8 · data-c06

How many more votes did soccer get than tennis?

Table. Columns: Sport, Votes. Rows: soccer, 12; baseball, 8; tennis, 5.
SportVotes
soccer12
baseball8
tennis5
  1. Read the table: soccer has 12 votes and tennis has 5.
  2. How many more asks for the difference between those counts.
  1. Subtract: 12−5=7 more soccer votes.
  2. Check: 5 tennis votes + 7 extra = 12 soccer votes.

Answer: 7

7 of 8 · data-c07

Median of this list?

Table. Columns: Value. Rows: 3; 5; 5; 8; 9; 12; 14.
Value
3
5
5
8
9
12
14
  1. Median is the middle of the ordered values.
  2. The table lists 3,5,5,8,9,12,14: seven entries. Count the repeated 5 twice.
  1. The fourth entry is 8, with three on each side; median = 8.
  2. Check: Cross off the smallest and largest remaining values three times; the one left is 8.

Answer: 8

8 of 8 · data-c08

Which is a random sample of all 7th graders? Choose A, B, or C. A: the first 10 in the lunch line. B: 15 names drawn from a hat of the whole grade. C: only the soccer team.

  1. A random sample of the grade should give every seventh grader a chance to be selected.
  2. B draws names from the whole grade, so anyone in that grade could be drawn.
  1. A only takes students from the front of the lunch line; C only takes soccer players. Those groups can leave out other students.
  2. Choose B. Check: a non-soccer student at the back of the line can still be selected by B.

Answer: B