The variable z is directly proportional to x. When x is 11, z has the value 44. What is the value of z when x = 16?

Answer 1

z = kx

44 = 11k

4 = k

z = (16)(4)

Answer 2

First pass: Find k, the proportionality constant.

"z is directly proportional to x" translates to math as z = k·x

Put it the information before the question is asked. 44 = k (11) and find that k=4

2nd pass: Start over, and solve for what they are asking.

Write proportion again, this time using 4 for k

z = 4·x

Now plug x = 16 into equation and find that z = 4(16) = 64