Going from 12 to 4 on an analog clock has us go 4 spaces. So 4/12 = 1/3 of the full circle is taken up. Meaning the angle the hands form is (1/3)*360 = 120
Think of the contents of the bag having 6 equal parts (in numerical quantity). Then the fraction of all the marbles which happen to be white marbles is 1/6. This converts to 16.67%.
