Question

Suppose that y is directly proportional to x and that y = 16 when x = 8. Find the constant of proportionality k.

Then, find y when x = 12.

Answer 1

Answer: 24

Explanation:

Variation: y ∞ x

y = kx , where k is the constant of proportionality

now to find k, we substitute for y and x in the equation above

16 = 8k

therefore,

k = ¹⁶/₈

= 2.

Now, to find y , we move back to the equation above and substitute for x and k to get y

y = 12(2)

= 24