Suppose that 1010% of a certain batch of calculators have a defective case, and that 1414% have defective batteries. Also, 5
5% have both a defective case and defective batteries. A calculator is selected from the batch at random. Find the probability that the calculator has a good case and good batteries.
If you look at the red blue and purple dots you can see that they form a straight line. if you connected the green dot to the line it would make the line not straight, therefore the relationship is not proportional.