In an examination, 80% students passed in Physics, 70% in Chemistry while 15% failed in both the subjects. If 325 students passed in both the subjects. Find the total number of students who appeared in the examination. (a) 500 (b) 400 (d) 600 (c) 300 answer-500 please explain

Let total students be 100x. Students passed in physics = 80x (A) Students passed in chemistry = 70x (B) Students failed in both = 15x Students passed in any or both subject = 100x - students failed in both subject = 100x-15x = 85x ( AUB) Students passed in both subjects = 325 (A intersection B) Now, A + B - (A intersection B) = AUB 80x + 70x - 325 = 85x 65x = 325 x = 5. So, total students = 100x = 100*5 = 500.