Question

If z is directly proportional to x and z=12 when.x=3. Find the value of x when z =18

Answer 1

GIVEN :

The variable z is directly proportional to x and z=12 when x=3.

TO FIND :

The value of x when z =18

SOLUTION :

Given that z is directly proportional to x and z=12 when x=3.

Now we have to find the value of x when z=18 :

The variable z is directly proportional to x.

When z is 12 , x has the value 3

A directly proportional variable z to x can be written as,

$z=kx$

 where k is constant of proportionality.

Now we have,

$\frac{x}{z}=\frac{3}{12}=k$  (∵  z=12 when x=3)

∴ $k=\frac{1}{4}$

Now put z=18 then $x=\frac{z}{k}$

Substitute the value of k in the above equation we get

$x=\frac{18}{\frac{1}{4}}$

$=72$

∴ x=72 when z=18.

∴ the value of x when z=18 is 72.

Answer 2

Answer:

x=4.5

Step-by-step explanation:

As we know,

z=kx     12=3k       k=12/3    k=4

z=4x     18=4x       x=18/4    x=4.5