Question

Is y varies directly as x, and y is 18 when x is 5 witch expression can be used to find the value of y when x is 11?

Answer 1

As the variation is direct we have:

`y = k * x`
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:

`18 = k * 5`
From here, let's clear k:

`k = 18/5 k = 3.6`
Then, replacing values we have:

`y = 3.6 * x`
For x = 11 we have:

`y = 3.6 * 11 y = 39.6`
Answer:
An expression that can be used to find the value of y when x is 11 is:

`y = 3.6 * x`
When x = 11 we have:

`y = 39.6`