Question

Suppose y varies directly as x and y = 20 when x = 8. What is the value ofy whenx = 12?

y =__

Answer 1

y = 30

Explanation:

Use the direct variation equation, y = kx

Plug in 20 as y and 8 as x, then solve for k:

y = kx

20 = k(8)

2.5 = k

So, the equation is y = 2.5x

Plug in 12 as x, and solve for y:

y = 2.5x

y = 2.5(12)

y = 30

So, when x = 12, y = 30