Line Plot (Dot Plot) Statistics Example 4

Follow the full solution, then compare it with the other examples linked below.

Example 4

hard
Two classes made line plots of their test scores. Class A: 70 (1), 75 (3), 80 (6), 85 (4), 90 (1). Class B: 60 (2), 70 (3), 80 (5), 90 (3), 100 (2). Compare the centres and spreads of the two distributions.

Solution

  1. 1
    Step 1: Class A mean = 70+225+480+340+9015=120515≈80.3\frac{70 + 225 + 480 + 340 + 90}{15} = \frac{1205}{15} \approx 80.3. Range = 90−70=2090 - 70 = 20. Class B mean = 120+210+400+270+20015=120015=80.0\frac{120 + 210 + 400 + 270 + 200}{15} = \frac{1200}{15} = 80.0. Range = 100−60=40100 - 60 = 40.
  2. 2
    Step 2: Both classes have nearly the same mean (~80), but Class B has double the range (40 vs 20), indicating much greater spread in scores.

Answer

Both classes have a mean of approximately 80, but Class B has a range of 40 compared to Class A's range of 20, so Class B's scores are more spread out.
Comparing line plots involves looking at both centre (mean or median) and spread (range). Two distributions can have similar centres but very different spreads, which tells us about the consistency or variability of the data.

About Line Plot (Dot Plot)

A line plot (also called a dot plot) is a diagram that displays data values as marks — usually X's or dots — stacked above their corresponding values on a number line. Each mark represents one data point, making it easy to see the frequency of each value.

Learn more about Line Plot (Dot Plot) →

More Line Plot (Dot Plot) Examples

Example 1 easy

Students measured the lengths of 10 leaves (in cm): 5, 6, 5, 7, 6, 5, 8, 6, 7, 5. Create a line plot

Example 2 medium

A line plot shows the number of hours students spent on homework: 1 hour (2 dots), 1.5 hours (4 dots

Example 3 medium

A line plot shows the weights of 12 apples in fractions of a pound: [formula] (3 dots), [formula] (5

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