The amount of chlorine needed to treat a swimming pool is directly proportional to the volume of the pool.
chlorine: volume of pool:
5 2500
10 5000
15 7500
What is the constant of proportionality for this relationship?
a. 0.002
b. 0.02
c. 0.2
d. 1/2
C = kV
Now just use one of the data points, how about the first one
5 = k(2500)
k = 5/2500 = .002
So C = .002V
(notice all the other given data points satisfy this equation)