Question

I’ve been having trouble with this question as I haven’t learnt it yet.

R is inversly proportional to A
R =12 when A =1.5
Work out the value of R when A=5
Work out the value of A when R=9

Answer 1

R =
`(18)/(5)` = 3.6 and A = 2

given that R is inversely proportional to A, then

R =
`(k)/(A)` ← k is the constant of variation

To find k use the condition R = 12 when A = 1.5

k = RA = 12 × 1.5 = 18

the equation is therefore

R =
`(18)/(A)`

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