Q: The average of seven numbers is 18. The average of first three numbers is 14 and the average of last three numbers is 19. What is the middle number?
Options:
(A) 27
(B) 29
(C) 30
(D) 34
(E) 35
A: OK... Stream of consciousness: The total of seven numbers = 7X18 = 126
The total of first 3 and last 3 numbers is = 3 X 14+3 X 19 = 99
So, the middle number is (126 - 99 ) = 27
The answer is (A).

Q: A boy runs 200 metres in 24 seconds. What is his speed ?
Options:
(A) 20 km/hr
(B) 24 km/hr
(C) 28.5 km/hr
(D) 30 km/hr
(E) 35 km/hr
A: OK... Stream of consciousness: 200/24 * 18/5 = 30 km/hr
The answer is (D).

Q: In what time will a railway train 30 m long moving at the rate of 36 kmph pass a telegraph post on its way?
Options:
(A) 5 sec
(B) 4 sec
(C) 3 sec
(D) 6 sec
(E) 1 sec
A: OK... Stream of consciousness: T = 30/36 * 18/5 = 3 se
The answer is (C).

Q: Calculate the speed of a boat in still water (in km/hr) if in one hour, the boat goes 13 km/hr downstream and 10 km/hr upstream.
Options:
(A) 3 kmph
(B) 9 kmph
(C) 4 kmph
(D) 8 kmph
(E) 6 kmph
A:
OK... Stream of consciousness: Speed in still water = (13 + 5)1/2 kmph = 9 kmph.
The answer is (B).