[tex]$y$[/tex] varies directly with [tex]$x$[/tex]. [tex]$y$[/tex] is 30 when [tex]$x$[/tex] is 6. What is [tex]$y$[/tex] when [tex]$x$[/tex] is 11?

[tex]\[
\begin{array}{c}
y = 5x \\
y = [?]
\end{array}
\][/tex]



Answer :

To solve this problem, we need to follow the concept of direct variation, which states that if [tex]\( y \)[/tex] varies directly with [tex]\( x \)[/tex], then [tex]\( y \)[/tex] can be expressed as:

[tex]\[ y = kx \][/tex]

where [tex]\( k \)[/tex] is the constant of variation.

### Step-by-Step Solution:

1. Find the constant of variation ([tex]\( k \)[/tex]):
- We are given that [tex]\( y \)[/tex] is 30 when [tex]\( x \)[/tex] is 6. Substitute these values into the direct variation equation to find [tex]\( k \)[/tex]:

[tex]\[ 30 = k \cdot 6 \][/tex]

- To solve for [tex]\( k \)[/tex], divide both sides of the equation by 6:

[tex]\[ k = \frac{30}{6} \][/tex]

- Simplify the fraction:

[tex]\[ k = 5 \][/tex]

2. Use the constant of variation [tex]\( k \)[/tex] to find the new [tex]\( y \)[/tex]:
- We need to find [tex]\( y \)[/tex] when [tex]\( x \)[/tex] is 11. Substitute [tex]\( x = 11 \)[/tex] and [tex]\( k = 5 \)[/tex] into the direct variation equation:

[tex]\[ y = kx \][/tex]

- Substitute the values of [tex]\( k \)[/tex] and [tex]\( x \)[/tex]:

[tex]\[ y = 5 \cdot 11 \][/tex]

- Perform the multiplication:

[tex]\[ y = 55 \][/tex]

Therefore, [tex]\( y \)[/tex] is 55 when [tex]\( x \)[/tex] is 11.