Question

X is inversely proportional to y. When x=3, y=27. Find x when y=9

Answer 1

x = 9

Explanation:

Given that x is inversely proportional to y then the equation relating them is

x =
`(k)/(y)` ← k is the constant of variation

To find k use the given condition that x = 3 when y = 27, thus

3 =
`(k)/(27)` ( multiply both sides by 27 )

81 = k

x =
`(81)/(y)` ← equation of variation

When y = 9, then

x =
`(81)/(9)` = 9

Answer 2

Explanation:

When something is inversely proportional it can be solved by using the equation:

y = k/x

where k is the constant.

So using this we can plug in x and y to find the value of k.

27= k/3

Next we isolate k and find that k = 81. Now we use this to find the value of x when y = 9. Plug in y and you get x = 81/9 or x = 9