Answer:
The correct answer is k=1/5
Step-by-step explanation:
Given the expression " r varies directly as p", we need to find an equation that describes the relationship between both variables. First, we have that r varies as p varies, so r is the dependent variable and p is the independent variable. So
r = k x p ⇒ replacing with the given values (r =3 when p =15)
3 = k x 15 ⇒ 3/15 = k ⇒ 1/5 = k.
Then the constant of proportionality is k = 1/5.