Final answer:
The third step in solving quantitative relationships is to identify the unknown quantities needed for the problem. Making a list of these unknowns is useful for organization. The subsequent steps involve finding the relevant equations and solving for these unknowns.
Step-by-step explanation:
The third step in solving quantitative relationships involves identifying exactly what needs to be determined in the problem, which is to say, identifying the unknown quantities. This is often achieved by making a written list, as it helps in organizing thoughts and ensuring that all the necessary variables are accounted for when setting up equations.
After identifying the unknowns, one should proceed with the fourth step, which is finding an equation or set of equations that can help solve the problem. Here, the list of knowns (previously established facts or given data) and unknowns will serve as a guide. In many cases, it's possible to use equations that contain only one unknown variable. However, if an equation has more than one unknown, then additional equations will be necessary.
Finally, the fifth step may involve solving the equation(s) determined in the previous step and analysing the results, which could include steps such as drawing a scatter plot, calculating correlation coefficients, and determining lines of best fit using methods like least-squares regression.