# Video: Using Straight Lines to Model Relationships between Two Quantitative Variables

The following scatter diagram shows the test results of two exams for a class of 26 students. If Sophia got 84 on exam 1, which of the following would you expect to be her score for exam 2? [A] 70 [B] 92 [C] 86 [D] 50 [E] 60

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### Video Transcript

The following scatter diagram shows the test results of two exams for a class of 26 students. If Sophia got 84 on exam one, which of the following would you expect to be her score for exam two?

Here our 𝑥-axis graphs what exam one test results are, and where our 𝑥s on the 𝑦-axis shows us what they got on exam two. For example, this first 𝑥 received a 44 on exam one and a 52 on exam two. This 𝑥 is in position 44, 52.

We want an estimate for Sophia who received an 84 on exam one. Sophia’s 𝑥-axis would be plotted at 84. Based on the data we’re given and other similar points, we would think that Sophia’s score on exam two would fall somewhere between 84 and 88, and only one of our answer choices falls in that range. A good estimate for Sofia’s score on exam two would be 86.