Which of the following is true regarding cross-sectional data sets? Check all that apply. The data are collected multiple times over several different time periods. The data consist of only one individual, tracked over time. Most observations are not independent across time. The data are collected at approximately the same point in time.

Suppose you are an avid reader and are looking to save money on the cost of books instead of paying about $20 for each book, you decide to look into purchasing a kindle for $120 you can purchase e-books for about $5 each 1. find the slope-intercept equation for the cost of the hard copy of books using x to represent the number of books 2. find the slope-intercept equation for the cost of the kindle with cost of e-books using x to represent the number of books