The Venn diagram above shows the number of students offering physics and chemistry in a class of 65. What is the probability that a student selected from the class offers physics and chemistry if every students offers at least one subject?
65 = 30 -x + x + 45 - x
65 - 75 = 10 = x ( number of students offering both subjects)
Pr( students offering both subjects) = 1065 = 213
