You are given a background paragraph that describes one or more causal or qualitative relationships such as a relationship in economics or a scientific law and a story that makes use of the concepts or the relationship described in the provided paragraph. You are also given a question about the story that requires an understanding of the relationship described in the background paragraph and the story. You need to come up with an answer to the given question; the answer will be a span from either the question or the story. In order to correctly answer the given question, you need to understand the relationship mentioned in the background paragraph and should be able to use it to understand that in the story. Your answer can not consist of any word that is not mentioned in any of these: the background paragraph, the story, or the question. You can directly copy and paste a span from the story or the question while answering the given question.

Background Paragraph: Turner et al (2006) derived crash prediction models for this report's predecessor and found a
pronounced 'safety in numbers' effect in the models. Using the crash prediction model for mid-block
locations, generic motorist and cyclist volumes can be used to demonstrate the impacts on the
expected crash rate of varying motor vehicle and cycle volumes. As shown in figure 2.20, an increase
in the proportion of cyclists to the overall traffic volume causes an increase in expected crashes at
mid-block locations, but the crash rate increases at a decreasing rate. That is to say, the crash rate per
cyclist goes down as the cycle volume increases.
Story: There were a lot of motorcycles on Interstate 15 last week. On Saturday, there were 1551 motorcyclists. On Sunday, there were 2551 motorcyclists. On Monday, there were 3551 motorcyclists. On Tuesday, there were 4551 motorcyclists. On Wednesday, there were 5551 motorcyclists. On Thursday, there were 6551 motorcyclists. On Friday, there were 7551 motorcyclists.
Question: What day had a lower crash rate per cyclist: Thursday or Friday?
Friday.

Background Paragraph: Regions on the Earth's surface (or in its atmosphere) that are high above mean sea level are referred to as high altitude. High altitude is sometimes defined to begin at 2,400 meters (8,000 ft) above sea level.[5][6][7]

At high altitude, atmospheric pressure is lower than that at sea level. This is due to two competing physical effects: gravity, which causes the air to be as close as possible to the ground; and the heat content of the air, which causes the molecules to bounce off each other and expand.[8].
Story: Riley has just been diagnosed with a disease that requires him to be in an area that has low atmospheric pressure to help his breathing. He has two cities he can choose to live in based on his current budget. Denver with an elevation of 10,000 ft, and Miami, which is around sea level.
Question: What city should Riley avoid moving to because it will most likely have higher atmospheric pressure?
Miami.

Background Paragraph: The stronger of two acids will have a higher Ka than the weaker acid; the ratio of hydrogen ions to acid will be higher for the stronger acid as the stronger acid has a greater tendency to lose its proton. Because the range of possible values for Ka spans many orders of magnitude, a more manageable constant, pKa is more frequently used, where pKa = log10 Ka. Stronger acids have a smaller pKa than weaker acids. Experimentally determined pKa at 25 C in aqueous solution are often quoted in textbooks and reference material.
Story: Jacob and Thomas were conducting an experiment in a chemistry class. The goal of the experiment was to identify the strength of unknown acids by examining the products formed in a chemical reaction. After they completed the experiment, Jacob concluded that he was given a strong acid, while Thomas concluded that he was given a weak acid.
Question: Which person's acid, Jacob's or Thomas's, will have a higher ratio of hydrogen ions to acid?
Jacob's.