Question

Suppose y varies jointly as x and z. Find y when x=-9 and z=23, if y=117 when x=-3 and z=-11. Round your answer to the nearest hundredth, if necessary. Select one:

Answer 1

-733.909

Explanation:

To find the answer to this question, we need to know the constant of variation.

The procedure to get the values is

Y ∞ X × Z

Y = k*x*z

When y = 117, x = -3 and z = -11

Put this values in that equation above and we have the value of X

117 = -11 × -3 × k

117 = 33k

K = 117/33

K = 3.545

Now that we have the constant of variation needed to get the value of either y,x or z whenever we have 2 other figures

So when x = -9 and z = 23

Y = -9 × 23 × 3.545

Y = -733.909

Answer 2

The value of y given the values of x and z in the question is -734.85

Explanation:

This is a joint variation question.

First, we are made to know that y varies jointly as x and z.

The equation for this can be written as;

y = k * x * z

Where k is the constant of proportionality.

Let’s calculate k first.

117 = k * (-3) * (-11)

33k = 117

K = 117/33 = 3.55

Now, we proceed to get what y is when x = -9 and z = 23

Let’s plug these values into the initial equation written.

y = k * x * z

We use the value of k calculated above;

y = 3.55 * (-9) * (23) = -734.85