Then: (A) \( k = \frac{1}{6} \) (B) \( P(X < 2) = \frac{1}{2} \) (C) \( E(X) = \frac{3}{4} \) (D) \( P(1 < X \leq 2) = \frac{5}{6} \) Choose the correct answer from the options given below:
It is known that 20% of the students in a school have above 90% attendance and 80% of the students are irregular. Past year results show that 80% of students who have above 90% attendance and 20% of irregular students get “A” grade in their annual examination. At the end of a year, a student is chosen at random from the school and is found to have an “A” grade. What is the probability that the student is irregular?