Question

If p varies directly as r and p=4,r=2,what the value of r when p=12

Answer 1

r = 6

Explanation:

Given that p varies directly as r, then the equation relating them is

p = kr ← k is the constant of variation

To find k use the condition p = 4, r = 2

k =
`(p)/(r)` =
`(4)/(2)` = 2

p = 2r ← equation of variation

When p = 12

12 = 2r ( divide both sides by 2 )

hence r = 6