Question

if y varies directly as x and y = 15 when x = 5, what is the value of y when x = 6?
a. 5
b. 36
c. 9
d. 18

please select the best answer from the choices provided

a
b
c
d

Explanation:

Step1: Define direct variation

For direct variation, \( y = kx \), where \( k \) is the constant of variation.

Step2: Find the constant \( k \)

Given \( y = 15 \) when \( x = 5 \), substitute into \( y = kx \):
\( 15 = k \times 5 \)
Solve for \( k \): \( k=\frac{15}{5}=3 \).

Step3: Find \( y \) when \( x = 6 \)

Now, use \( k = 3 \) and \( x = 6 \) in \( y = kx \):
\( y = 3 \times 6 = 18 \).

Answer:

D. 18