From the diagram we get that:
1) The total number of people in the study is 661+106+40+60+239+102+172+86=1466.
2) The total number of people that tried to quit smoking using lozenge given that they did not use gum is 60+172=232.
Therefore, the probability that a randomly selected person from this study tried to quit smoking using a lozenge given that they did not use gum is:
Answer: 0.1583 or 15.83%.