What is the value of y when x=9?

Question

The value of y is inversely proportional to the value of x. When y=42, x=6. What is the value of y when x=9? 

Answer 1

Since y is inversely proportional to x, there is a constant k such that y = k/x

This is the same as k = y * x

 

If y = 42 and x = 6, then k = y * X = 252.

 

When x = 9, 9y = 252 and so y = 28

Answer 2

Inversely proportional means that the relation between y and x is of the form

 

y = c/x

 

where c is a constant.

 

Get c from knowing y=42 when x=6.

 

42 = c/6

 

Then c = 6*42 = 252

 

Therefore,

 

y = 252 / x

 

For x=9,

 

y = 252/9 = 28