Line Plots — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A Grade 3 student lists shoe lengths: 7, 7.5, 7.5, 8, 8, 8. After plotting, which value is the mode?
A) 7
B) 7.5
C) 8
D) 8.5
The value 8 appears three times, more than 7 (once) or 7.5 (twice), so 8 is the mode of this data list.
2. A Grade 3 line plot uses 0.5-inch steps from 5 in to 7 in. How many labeled marks are on the scale?
A) 3 marks
B) 4 marks
C) 5 marks
D) 6 marks
Going by half-inch steps from 5 to 7 gives the labels 5, 5.5, 6, 6.5, and 7 inches, which is 5 labeled marks.
3. A Grade 3 line plot of bean plant heights shows 3 Xs at 4 in, 5 Xs at 4.5 in, 2 Xs at 5 in. How many plants in total?
A) 8 plants
B) 9 plants
C) 10 plants
D) 11 plants
Total plants is the sum of all Xs: 3 plus 5 plus 2 equals 10 bean plants measured for the line plot.
4. On a Grade 3 line plot of pencils from 3 in to 6 in, what is the range of pencil lengths?
A) 1 in
B) 2 in
C) 3 in
D) 4 in
Range equals largest minus smallest value: 6 inches minus 3 inches equals a 3-inch range across the line plot.
Part B: Fill in the Blank
Write the correct answer on each line.
1. Sam measured worms: 2.5, 3, 3, 3.5. He puts 2 Xs above 3 inches on his Grade 3 line plot.
The value 3 inches appears two times in Sam's data list, so he stacks 2 Xs above 3 on the line plot.
2. A Grade 3 line plot of crayons has 4 Xs above 3 in and 6 Xs above 3.5 in, so 10 crayons total so far.
Total crayons so far equals the sum of column counts: 4 Xs plus 6 Xs equals 10 crayons measured.
3. A Grade 3 line plot has Xs above 2, 2.5, 3, and 3.5 in. The smallest value, 2 in, is the low of the range.
The smallest scale value with data is the low end of the range, so 2 inches is the low end of this line plot.
4. If a Grade 3 line plot shows 6 total Xs and one column with 6 Xs, then only 1 value was measured.
If all 6 Xs sit in one column, only one scale value was measured because every data point matched the same length.
5. A Grade 3 line plot has 3 Xs at 5 in, 1 X at 5.5 in, 4 Xs at 6 in. The most common length is 6 inches.
The tallest stack has 4 Xs above 6 inches, so 6 inches is the most common length, also called the mode.