4-8: Direct and Inverse Variation

These web-based activities were developed, during summer sessions from 1997 through 1999, by students at Mainland High School, located in Daytona Beach, FL. As part of Mainland's CCTT grant, the students were given permission by the book's publisher to convert the ancillary materials of the County's adopted Algebra 1 Textbook into html format.

Practice
Direct and Inverse Variation

Directions: Solve. Assume that y varies directly as x. [Remember that a direct variation is described by an equaion of the form y = kx where k≠0.]

1. If y = −4 when x = 2, find y when x = −6.

3. If y = −5 when x = 12.5, find x when y = 15.

5. If y = 80 when x = 32, find x when y = 100.

7. If y = 28 when x = 168, find y when y = 108.

2. If y = 16 when x = 4. find y when x = 6.

4. If y = 7 when x = 4, find y when x = 12.

6. If y = 198 when x = 22, find y when x = 182.

8. If y = 24 when x = 6, find y when x = −4.

Directions: Solve. Assume that y varies inversely as x. [Remember that an inverse variation is described by an equaion of the form xy = k where k≠0.]

9. If y = −4 when x= 2, find y when x = −6.

11. If y = −5 when x = 12.5, find x when y = 15.

13. If y =27 when x = 12, find x when y = −12.

15. If y = 60 when x = 80, find x when y = −20.

10. If y = 16 when x = 4, find y when x = 6.

12. If y = 7 when x = 4, find y when x = 12.

14. If y = 6 when x = −4, find x when y = ¹²/₅.

16. If y = 40 when x = 16, find y when x = 10.