Question

The variable y is directly proportional to the variable x. If y = 32 when x = 20, what is the value of x when y = 40?

A)
20


B)
20.5


C)
25


D)
30

Answer 1

The Correct option is C ) 25

Therefore the value of x is 25 when y =40.

Explanation:

Given:

Variable 'y' is directly proportional to the variable 'x'.

`\therefore y=kx` ......Direct Variation

Where,

k = Constant of proportionality

To Find:

value of x = ? when y = 40

Solution:

First we need to find Constant of proportionality

When x = 20 and y = 32

Substituting the values we get

`32=k* 20\\k=(32)/(20)=1.6\\\\k=1.6`

Now when k =1.6 , y = 40 then x will be

`40=1.6* x\\\\x=(40)/(1.6)=25\\\\x=25`

Therefore the value of x is 25 when y =40.