Question

R is inversely proportionate to a

when r = 12 a = 1.5
work out the value of r when a = 5
work out the value of a when r = 9

Answer 1

r = 3.6 , a = 2

Explanation:

given that r is inversely proportional to a then the equation relating them is

r =
`(k)/(a)` ← k is the constant of proportion

to find k use the condition when r = 12 , a = 1.5

12 =
`(k)/(1.5)` ( multiply both sides by 1.5 )

18 = k

r =
`(18)/(a)` ← equation of proportion

when a = 5 , then

r =
`(18)/(5)` = 3.6

when r = 9 , then

9 =
`(18)/(a)` ( multiply both sides by a )

9a = 18 ( divide both sides by 9 )

a = 2