1) A hypothetical cohort study of 1800 people was done to examine the association between exposure to vaping and periodontal bone loss. The results are displayed in the table below. Please show your all calculations and report values to 2 decimal places. (7 Marks) Periodontal No periodontal Total bone loss bone loss Vaping 120 775 895 No vaping 50 855 905 Total 170 1630 1800 a] What is the risk of periodontal bone loss among those exposed to vaping? Show calculation. (1.5 Marks) b) What is the risk of periodontal bone loss among those who are not vaping? Show calculation. (1.5 Marks) c) Calculate the number needed to treat. Show calculation. (2 Marks) d) Interpret the value of the number needed to treat from part C in a single statement. (2 Marks)