Jointly Proportional

Definition of Jointly Proportional

If a variable z is jointly proportional to a set of variable x and y, the z = kxy, where k is the constant of proportionality.

More About Jointly Proportional

    Jointly proportional is also known as joint variation.

Example of Jointly Proportional

    The kinetic energy, E, of a moving object is jointly proportional to its mass, m, and the square of its speed, v.i.e., E = k .m. v2

Video Examples: Art of Problem Solving: Joint Proportion

Solved Example on Jointly Proportional

Ques: If x is jointly Proportional to y and z when x = 4, y = 8 and z = 9, then find the value of x when y = 2 and z = 18.

    A. 1
    B. 0
    C. 2
    D. 4
    Correct Answer: C


    Step 1: x a k. y. z [joint proportional]
    Step 2: x = k. y. z
    Step 3: 4 = k. 8. 9 [Substituting the values for x, y, z.]
    Step 4: k = 1/18[Simplify.]
    Step 5: Therefore, x =1/18. 2. 18 [Substituting the values for k, y and z in x = k. y. z]
    Step 6: So, x = 2 [Simplify.]

Translate :

Please provide your email for a free trial as a Teacher or Student. This trial will be valid for the current academic year (2015-16). An email to this address includes the password to login to the full web application. You will also receive other promotional emails as and when such deals become available.

I am a Teacher Student