As the variation is direct we have:
[tex]y = k * x
[/tex]
Where,
k: proportionality constant
We must find the value of k.
For this we use the following data:
y is 18 when x is 5.
Substituting values we have:
[tex]18 = k * 5
[/tex]
From here, let's clear k:
[tex]k = 18/5
k = 3.6
[/tex]
Then, replacing values we have:
[tex]y = 3.6 * x
[/tex]
For x = 11 we have:
[tex]y = 3.6 * 11
y = 39.6[/tex]
Answer:
An expression that can be used to find the value of y when x is 11 is:
[tex]y = 3.6 * x
[/tex]
When x = 11 we have:
[tex]y = 39.6[/tex]
