Direct Joint Combined Variation

Solve for the constant of variation, k.

A varies directly as D and inversely as F. A=10.5, when D=2 and F=4

If y varies directly as x and inversely as z, and y = 24 when x = 48 and z = 4, find x when y = 44 and z = 6.

• 126

• 132

• 148

• 154

The amount of money earned on a job is directly proportional to the number of hours worked. if $36 is earned for 8 hours of work, how much is earned for 30 hours of work?

• 135

• 6.667

• 1080

Which of the following represents direct variation?

• y = kx

• y = k/x

• y = x/k

• y = mx + b

Write the given statement in a mathematical equation.

r varies jointly as s and w

• r = ksw

• w = ksr

Solve for the constant of variation, k.

y varies jointly as x and z.   x = -2 when y = 24 and z = -4

The variable x is in joint variation with y and z. When the values of y and z are 4 and 6, respectively, x is 72. What is the value of x when y = 2 and z =8?

• 32

• 48

• 64

• 96

If y varies jointly with the product of x and z, and y = 1000 when x = 10 and z = 20, find y when x = 8 and z = 10.

• 100

• 300

• 200

• 400

Write the mathematical equation of the given statement: (no spacing, use / for fraction bar)

The time (t) needed to answer a set of problems is directly proportional to the number (N) of problems, and inversely proportional to the number of students (P) working on the solutions.

If f varies directly as g and inversely as the square of h, and f = 20 when g = 50 and h = 5, find f when g = 18 and h = 6.

• 4

• 5

• 8

• 10