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?

A) y = 11
B) y = 5(11)
C) y = (18)(5)
D) y = (18/5)(11)

Answer 1

To find the value of y when x is 11, we can use the equation for direct variation: y = kx, where k is the constant of variation. We can find the value of k by substituting the given values of x and y into the equation. The expression that can be used to find the value of y when x is 11 is y = (18/5)(11), which is option D.

Step-by-step explanation:

To find the value of y when x is 11, we can use the equation for direct variation: y = kx, where k is the constant of variation. We can find the value of k by substituting the given values of x and y into the equation.

Given that y is 18 when x is 5, we have: 18 = k(5). Solving for k, we find k = 18/5.

Now we can use the value of k to find the value of y when x is 11: y = (18/5)(11).

Therefore, the expression that can be used to find the value of y when x is 11 is y = (18/5)(11), which is option D.