The bar chart represents the distribution of marks scored by students in an economics examination. If the fail mark was 4, what is the probability that a student selected at random passed?
Marks 1–8 with frequencies 3, 6, 9, 1, 12, 7, 5, 10.
Worked solution (try it first)
Read the bars and add: 3+6+9+1+12+7+5+10=53 students.
A fail mark of 4 means a pass needs more than 4 marks: marks 5 to 8, which is 12+7+5+10=34 students.
So the probability of a pass is 5334≈0.64, option A.