# 4 2 Writing Equations given Word Problems Goal

4 -2 Writing Equations given Word Problems Goal: Use a linear equation to model a real-life problem. Eligible Content: A 1. 1. 2. 1. 1 / A 1. 1. 2. 1. 3 / A 1. 2. 1. 1. 1 / A 1. 2. 2. 1. 3 / A 1. 2. 2. 1. 4

Word Problems �Slope still means rate of change (y per x). �y-intercept still means beginning amount. �Ordered pairs are created by pairing up numbers that go together.

Word Problem #1 Billy is charged $50 to rent a car for the week. He also has to pay $. 25 per mile. Slope is $ per mile �Write a linear equation that models this situation. y =. 25 x + 50 �Use your equation to find the charge for 75 miles. $68. 75

Word Problem #2 Wanda hires someone to fix her heater. She is told that she will be charged a base fee and $45 per hour. Her bill is $215 and it took 2 hours to fix her heater. Slope is $ per hour �Write a linear equation that models this situation. y = 45 x + 125 �Use your equation to find the charge for 3. 5 hours. $282. 50

Word Problem #3 A camp program charges a registration fee and a daily amount. The total bill for 12 days is $338. The total bill for 19 days is $506. Slope is $ per day �Write a linear equation that models this situation. y = 24 x + 50 �Use your equation to find the charge for 30 days. $770

Word Problem #4 �

Word Problem #5 In 2004, there were 9. 97 million domestic flights in the US. In 2008, there were 9. 37 million domestic flights. Let x = 0 correspond to 2000. Slope is flights per year �Write a linear equation that models this situation. y = – 0. 15 x + 10. 57 �Use your equation to find the number of domestic flights in 2013. 8. 62 million flights

The cost of a textbook that Mrs. Lambert uses in her class was $57. 65 in 2005. She ordered more books in 2008 and the price increased to $68. 15. Write a linear equation to estimate the cost of a textbook. Let x represent years since 2005. A. y = 3. 5 x + 57. 65 B. y = 3. 5 x + 68. 15 C. y = 57. 65 x + 68. 15 D. y = – 3. 5 x – 10

Practice �Worksheet – “ 4 -2 Word Problems”

Homework �Pages 229 -230 #24, 31, 32, 40, 41, 42 Do not graph!

- Slides: 10