Question

The variable z is directly proportional to x, and inversely proportional to y. When x is 4 and y is 13, z has the value 1.2307692307692. What is the value of z when x= 9, and y= 20

Answer 1

Answer:

Step-by-step explanation:

1.2307692307692.

The first step is to find the proportionality constant.

The formula is

z = kx/y

1.2307692307692 = k * 4/13          Multiply both sides by 13

1.2307692307692 * 13 = 4k

16 = 4*k                                            Divide by 4

k = 16/4

k = 4

=================================

z = k*x/y

x = 9

y = 20

k = 4

z = 4 *9/20

z = 36/20

z = 1.8

Answer 2

Answer:

$&\boxed{\text{1.800 000 000 0000}}$

Step-by-step explanation:

$z \propto x\\\\z \propto \dfrac{1}{y}\\\\z \propto \dfrac{x}{y}\\\\z = k \left (\dfrac{x}{y} \right )$

Solve for k

$\begin{array}{rcl}1.2307692307692& = & k\left (\dfrac{4}{13} \right )\\\\16.000000000000 & = & 4k\\k & = & 3.9999999999999\\\\z & = & 3.9999999999999\left (\dfrac{x}{y}\right )\\\end{array}$

Calculate the new value of z

$\begin{array}{rcl}z & = & 3.999 999 999 9999 \left (\dfrac{9}{20}\right )\\\\& = &\boxed{\textbf{1.800 000 000 000}}\\\end{array}$