P, Q, R and S are to be uniquely coded using a and . If P is coded as aa and Q as a, then R and S, respectively, can be coded as (A) a and (B) B and ac (C) a and (D) a and a 8. The sum of the first n terms in the sequence 8, 88, 888, 8888, ... is 80 8 (A) (10-1)+n 81 9 (C) 81 (10-1)--n 80 81 (B) 80 (10-1)+2n (D) 80 (10-1)-9n 81 9. The bar graph shows the data of the students who appeared and passed in an examination for four schools P, Q, R and S. The average of success rates (in percentage) of these four schools is Performance of Schools P, Q, R and S Appeared Passed 700 Number of students 800 700 600 600 500 500 400 330 280 300 200 100 455 400 240 0 School P School Q School R School S (A) 59.0% (B) 59.3% (C) 58.5% M (D) 58.8%