Question

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

Answer 1

Answer:

Option b is correct

$y=\frac{18}{5}(11)$

Step-by-step explanation:

The direct variation says that:

$y \propto x$, then the equation is of the form:

$y=kx$ where, k is the constant of variation.

As per the statement:

If y varies directly as x.

By direct variation:

$y = kx$                ....[1]

If y = 18 when x = 5

Substitute these values in [1] we have;

$18 = 5k$

Divide both sides by 5 we have;

$\frac{18}{5}= k$

or

$k = \frac{18}{5}$

⇒$y = \frac{18}{5}x$                 ......[2]

We have to find the value of y when x = 11.

Substitute x = 11 in [2] we have;

$y = \frac{18}{5} \cdot 11 = \frac{18}{5}(11)$

Therefore, the value of y is, $\frac{18}{5}(11)$

Answer 2

B. 18/5(11), because when solving for k using the equation y=kx than you get 18/5 and then multiply by 11.