WAEC Mathematics 1988 Question 48

The surnames of 40 children in a class are arranged in alphabetical order. 16 of the surnames begin with O and 9 of the surnames begin with A. 14 of the letters of the alphabet do not appear as the first letter of a surname. What is the probability that the surname of a child picked at random from the class begins with either O or A?

1. A.5/8
2. B.7/8
3. C.9/16
4. D.14/25
5. E.31/40