﻿ Definition and examples jointly proportional | define jointly proportional - Free Math Dictionary Online

# 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.

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

### Solved Example on Jointly Proportional

A. 1
B. 0
C. 2
D. 4

#### Solution:

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.]

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