Answer: 1210

Explanation:
Number of students who did not pass in School B
=> 1100 x 66 / 100 = 726
=> Number of students, who did not pass in school C
=> = 1100 x 44 / 100 = 484
=> 726 + 484 = 1210

Answer: 16:21

Explanation:
ratio of the total number of students in A and F = 8/13.
=> Ratio of the number of students, who failed, in both the schools
=> = 8 x 52 / 13 x 42 = 16 : 21

Answer: 5:6 

Explanation:
let us assume that the total number of students in school D in
=> 1998 – 1999 = 100
=> In 1999-2000 it is 120
=> Now given, number of students who failed in 1999-2000
=> 70 x 120 / 100 = 84
=> Number of students who failed in 1998-2000
=> 100 x 84/120 = 70
=> Required ratio = 70/84 = 5:6

Answer: None of these

Explanation:
total number of students appeared in exam in School D
=> 140 x 100 / 70 = 200

Answer: 3:4

Explanation:
Let us assume that the total number of students appeared for exams in the given six schools = 1000. Number of students who appeared for exams in school
=> A = 2000
=> That in school E = 2500
=> Number, of students who failed in school
=> A = 2000 x 52 / 100 = 1040
=> Number of students who failed in school
=> E = 2500 x 55 / 100 = 1375
Required ratio = 1040/1375 = 208/275 = ¾