q: A and B can do a work in 12 days, B and C in 30 days and C and A in 36 days. In how many days will the work be completed, if all three of them work together?
Options:
(A) 189/13 days
(B) 188/13 days
(C) 180/13 days
(D) 180/17 days
(E) 280/13 days
a: OK... One day work of A and B = 1/12
One day work of B and C = 1/30
One day work of C and A = 1/36
2(A + B + C) = 1/12 + 1/30 + 1/36
2(A + B + C) = 13/90
(A + B + C) = 13/180
Number of days required = 180/13 days.
The answer is (C).

q: In how many different ways can the letters of the word "AIM" be rearrangement?
Options:
(A) 4
(B) 2
(C) 7
(D) 9
(E) 6
a: OK... Option 'E'
The total number of arrangements is
3P3 = 3! = 6
The answer is (E).

q: A train of 24 carriages, each of 60 meters length, when an engine also of 60 meters length is running at a speed of 60 kmph. In what time will the train cross a bridge 1.1 km long?
Options:
(A) 2 mins 14 sec
(B) 2 mins 34 sec
(C) 156 sec
(D) 134 sec
(E) 2 mins 44 sec
a:
OK... D = 25 * 60 + 1100 = 2600 m
T = 2600/60 * 18/5 = 156 se
The answer is (C).