Question

The value of y varies jointly with x and z. If y = 4 when z = 20 and x = 10, find the value of y when x = 2 and z = 68.

a) y = 0.50
b) y = 17
c) y = 2.72
d) y = 34

Answer 1

To solve the problem, we first found the constant of proportionality (k), and then substituted the new values of x and z to find y. The final value of y when x = 2 and z = 68 is 2.72.

Step-by-step explanation:

The problem states that the value of y varies jointly with x and z. This means that we have a direct relationship between these variables that can be expressed as y = kxz, where k is the constant of proportionality. When y = 4 given that z = 20 and x = 10, we can find the value of k by rearranging the formula to k = y / (xz). Plugging in the known values, we get k = 4 / (10*20) which simplifies to k = 0.02.

Now we want to find the value of y when x = 2 and z = 68. We plug these values into our original equation with the known k to get y = 0.02 * 2 * 68. This results in y = 2.72. Therefore, the answer is c) y = 2.72.