Question

Y is inversely proportional to x.
When y = 12, x = 10
Work out x when y = 30

Answer 1

x = 4

Explanation:

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

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

to find k use the condition when y = 12 , x = 10

12 =
`(k)/(10)` ( multiply both sides by 10 )

120 = k

y =
`(120)/(x)` ← equation of proportion

when y = 30 , then

30 =
`(120)/(x)` ( multiply both sides by 30 )

30x = 120 ( divide both sides by 30 )

x = 4