1. Warm Up
1. Points (7, y) and (1, 3) are on a line that have a slope of 2/5 . Find the value of y.
2. Which of the following equations represent a direct variation? What is k?
a) y = -2x b) y + x = -10 c) y = .5x
3. Write the equation of a horizontal line through the point (-4, 5).

2. HW Check 4.8

3. Use proportions to solve direct
variation word problems.
1) Assume a varies directly with b. If a = 6 when b = 9, what is the value of b when a = 4?

4. A dripping faucet wastes a cup of water if it drips for three minutes
A dripping faucet wastes a cup of water if it drips for three minutes. The amount of water wasted varies directly with the amount of time the faucet drips. Find the constant of variation, and write an equation.

5. Word Problems #2

6. #3
The Height of an object varies directly with the length of its shadow. A person 6 ft tall casts an 8.5 ft shadow, while a tree casts a 38 ft shadow. How tall is the tree?

7. #4
Your distance from lightning varies directly with the time it takes you to hear thunder. If you hear thunder 10 seconds after you see lightning, you are about 2 miles from the lightning. If you hear thunder 40 seconds after you see lightning, how far are you from the lightning?

8. #5
Weight varies directly with gravity. With his equipment on an astronaut weighs 360 lbs on Earth but only 60 lbs on the moon. If another astronaut had landed on the moon that weighed 54 lbs with her equipment, how much would she weigh on Earth with equipment?

9. Practice Worksheet