Page 134

miller_intermediate_algebra_4e_ch1_3

174 Chapter 2 Linear Equations in Two Variables and Functions Solution: a. The equation y 0.14x 1.60 is written in slope-intercept form.The slope is 0.14 and indicates that minimum hourly wage rose an average of $0.14 per year since 1970. b. The y-intercept is (0, 1.60).The y-intercept indicates that the minimum 1x 02 wage in the year 1970 was approximately $1.60 per hour. c. The year 1985 is 15 years after the year 1970. Substitute into the linear equation. y 0.14x 1.60 x 15 y 0.141152 x 15. 1.60 Substitute y 2.1 1.60 y 3.70 According to the linear model, the minimum wage in 1985 was approximately $3.70 per hour. (The actual minimum wage in 1985 was $3.35 per hour.) Skill Practice One cell-phone plan charges a monthly fee plus a charge per minute for the number of minutes used beyond 400 min. If a customer exceeds the 400-min cap, then the monthly fee, y (in dollars), is given by y 0.40x 49.99, where x is the number of minutes used beyond 400 min. 4. What is the slope? Interpret its meaning in the context of the problem. 5. What is the y-intercept? 6. Use the equation to determine the cost of using 445 min in this plan. 3. Finding a Linear Model from Observed Data Points Graphing a set of data points offers a visual method to determine whether the points follow a linear pattern.When two variables are related, it is often desirable to find a mathematical equation (or model) to describe the relationship. Answers 4. The slope is 0.40. The customer is charged $0.40 for each minute used beyond 400 min. 5. The y-intercept is (0, 49.99). This means that if 0 min is used beyond 400 min, the customer is charged $49.99. Writing a Linear Model from Observed Data Example 3 Figure 2-27 represents the number of women, y (in thousands), who graduated from law school in the United States by year. Let x represent the number of years since 1980. Number of Women Graduating from Law School by Year 24 20 16 (25, 19.7) 12 8 4 (15, 16.8) 0 0 5 10 15 20 25 30 35 Thousands Year (x 0 represents 1980) Source: U.S. National Center for Education Statistics 6. $67.99 Figure 2-27


miller_intermediate_algebra_4e_ch1_3
To see the actual publication please follow the link above