# Suppose that y is directly proportional to x and that y= 10 when x= 3. Find the constant of...

## Question:

Suppose that y is directly proportional to x and that y= 10 when x= 3. Find the constant of proportionality k.

## Constant of proportionality

The constant of proportionality is used to define the direction of the inverse relationship between the numbers. Two value inversely proportional to each other when one value increases, then the second value decrease.

## Answer and Explanation:

The expression according to the question is,

{eq}\begin{align*} y &\propto x\\ y &= kx \end{align*} {/eq}

Here the constant of proportionality is {eq}k {/eq}.

{eq}\begin{align*} 10 &= k \times 3\\ k &= \dfrac{{10}}{3}\\ &= 3.33 \end{align*} {/eq}

Thus, the value for k is {eq}3.33 {/eq}

#### Learn more about this topic:

Identifying the Constant of Proportionality

from 6th-8th Grade Math: Practice & Review

Chapter 50 / Lesson 13
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