Line Plots — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
A line plot shows pencil lengths in inches: 38→2 Xs, 48→5 Xs, 58→3 Xs, 68→4 Xs. A student says the range is 68 inch.
Corrected: The range is 68 − 38 = 38 inch. The range is the difference between the greatest and least values, not just the greatest value.
Range means the difference between the greatest and least values, not just the greatest value itself. Subtracting 68 − 38 gives a range of 38 inch.
2. Fix the sentence:
A line plot shows seed weights in grams: 14→4 Xs, 24→3 Xs, 34→6 Xs. A student says 6 seeds weigh less than 34 gram.
Corrected: Seeds weighing less than 34 gram: 14(4) + 24(3) = 7 seeds, not 6. The student miscounted the data points.
Seeds at 14 gram (4) plus seeds at 24 gram (3) equals 7 seeds weighing less than 34 gram, not 6. The student forgot to count all the X marks at both values below 34.
3. Fix the sentence:
A line plot shows clay weights in pounds: 18→3 Xs, 28→5 Xs, 38→1 X, 48→4 Xs. A student says there are 4 different values and 4 data points.
Corrected: There are 4 different values, but there are 13 data points (3 + 5 + 1 + 4 = 13). Each X mark is one data point, not each value on the number line.
While there are 4 different values on the number line, every single X mark counts as one data point. Adding 3 + 5 + 1 + 4 gives 13 total data points, not 4.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A line plot shows string lengths in feet: 14→5 Xs, 24→2 Xs, 34→4 Xs, 1→3 Xs. The value with the most X marks is 14.
The value 14 has 5 X marks, which is more than any other value (24 has 2, 34 has 4, and 1 has 3). The tallest column of Xs shows the most frequent value.
2. Using the string data, the total number of strings measured is 14.
Add all the X marks together: 5 + 2 + 4 + 3 = 14. Each X on the line plot represents one string that was measured.
3. A line plot shows sugar in cups: 18→4 Xs, 28→2 Xs, 38→6 Xs, 48→3 Xs. The number of recipes that use 38 cup or more is 9.
Recipes using 38 cup or more include those at 38 (6 Xs) and 48 (3 Xs). Adding 6 + 3 gives 9 recipes that meet the condition.
4. Using the sugar data, the difference between the number of recipes using 38 cup and the number using 28 cup is 4.
The 38 cup value has 6 X marks and the 28 cup value has 2 X marks. Subtracting 6 − 2 = 4 gives the difference in frequency between these two values.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. A line plot shows leaf widths in inches: 14→3 Xs, 12→6 Xs, 34→2 Xs, 1→4 Xs. How many leaves are wider than 12 inch? How many are 12 inch or narrower? Which group has more?
Sample answer: Wider than 12 inch: 34(2) + 1(4) = 6 leaves. At 12 inch or narrower: 14(3) + 12(6) = 9 leaves. The 12 inch or narrower group has more.
A good answer includes: Wider than 12 inch: 34(2) + 1(4) = 6 leaves. At 12 inch or narrower: 14(3) + 12(6) = 9 leaves. The 12 inch or narrower group has more.
2. A line plot shows rope lengths in yards: 18→2 Xs, 38→5 Xs, 58→3 Xs, 78→1 X. What is the total length of all the ropes? Show your work.
Sample answer: Multiply each value by its count and add: (2×18) + (5×38) + (3×58) + (1×78) = 28 + 158 + 158 + 78 = 398 = 478 yards total.
A good answer includes: Multiply each value by its count and add: (2×18) + (5×38) + (3×58) + (1×78) = 28 + 158 + 158 + 78 = 398 = 478 yards total.