question: A and B can do a work in 10 days and 15 days respectively. A starts the work and B joins him after 2 days. In how many days can they complete the remaining work?
Options:
(A) 6 days
(B) 2 days
(C) 4 4/5 days
(D) 3 days
(E) 9 days
answer: Stream of consciousness: Work done by A in 2 days = 2/10 = 1/5
Remaining work = 4/5
Work done by both A and B in one day = 1/10 + 1/15 = 5/30 = 1/6
Remaining work = 4/5 * 6/1 = 24/5 = 4 4/5 days. The answer is (C).

q: The average of seven numbers is 15. The average of first three numbers is 14 and the average of last three numbers is 19. What is the middle number?
Options:
(A) 6
(B) 29
(C) 31
(D) 34
(E) 35
a: Stream of consciousness: The total of seven numbers = 7X15 = 105
The total of first 3 and last 3 numbers is = 3 X 14+3 X 19 = 99
So, the middle number is (105 - 99 ) = 6 The answer is (A).

question: Eddy and Freddy start simultaneously from city A and they travel to City B and City C respectively. Eddy takes 3 hours and Freddy takes 4 hours to complete the journey. If the distance between City A and City B is 480 kms and City A and City C is 300 kms. What is the ratio of their average speed of travel? (Eddy: Freddy)
Options:
(A) 32/15
(B) 3/8
(C) 8/5
(D) 5/8
(E) 5/3
answer: Stream of consciousness: Distance traveled by Eddy = 480 km
Time taken by Eddy = 3 hours
Average speed of Eddy = 480/3 = 160 km/hour
Distance traveled by Freddy = 300 km
Time taken by Freddy = 4 hours
Average speed of Freddy = 300/4 = 75 km/hour
Ratio of average speed of Eddy to Freddy = 160/75 = 32/15 The answer is (A).

q: A 600 meter long train crosses a signal post in 40 seconds. How long will it take to cross a 3 kilometer long bridge, at the same speed?
Options:
(A) 2
(B) 3
(C) 4
(D) 1
(E) 8
a: Stream of consciousness: S = 600/40 = 15 mps
S = 3600/15 = 240 sec = 4 min The answer is (C).

question: A train 640 m in length crosses a telegraph post in 16 seconds. The speed of the train is?
Options:
(A) 22 kmph
(B) 77 kmph
(C) 144 kmph
(D) 71 kmph
(E) 88 kmph
answer: Stream of consciousness: S = 640/16 * 18/5 = 144 kmph The answer is (C).

question: 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
answer:
Stream of consciousness: Option 'E'
The total number of arrangements is
3P3 = 3! = 6 The answer is (E).