Lesson 13: Variations

Given: y varies directly as x, and y = 24 when x = 4.

What is the constant of variation?

• 1/6

• 6

• 20

• 28

Given: y varies directly as x, and y = 24 when x = 4.

What is the value of y when x = 3?

• 1/2

• 18

• 60

• 84

Given: y varies inversely as x, and y = 20 when x = 1/2.

What is the constant of variation?

• 1/40

• 5

• 10

• 40

Given: y varies inversely as x, and y = 20 when x = 1/2.

What is the value of x when y = 5?

• 1/8

• 2

• 40

• 50

Given: y varies jointly as x and z, and y = 8 when x = 12 and z = 2.

What is the constant of variation?

• 1/3

• 3

• 36

• 48

Given: y varies jointly as x and z, and y = 8 when x = 12 and z = 2.

What is the value of z when x = 12 and y = 16?

• 1

• 4

• 1/4

• 4/9

Given: The frequency (f) of a vibrating string varies inversely as its length (L). A string 3 feet long vibrates 175 cycles per second.

Which variation illustrates the problem?

Given: The frequency (f) of a vibrating string varies inversely as its length (L). A string 3 feet long vibrates 175 cycles per second.

What is the frequency of a 7-foot string? ___ cycles per second.

• 35

• 49

• 75

• 105

Given: Your distance (d) from lightning varies directly with the time (t) it takes you to hear thunder. If you hear thunder 10 seconds after you see the lightning, you are about 2 miles from the lightning.

Which variation illustrates the problem?

Given: Your distance (d) from lightning varies directly with the time (t) it takes you to hear thunder. If you hear thunder 10 seconds after you see the lightning, you are about 2 miles from the lightning.

If you are 6 miles form the lightning, after how many seconds will you hear the thunder? ___seconds

• 5

• 11

• 25

• 30