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: OK... 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).

Q: 80 370 860 1550 2440 ?
Options:
(A) 900
(B) 840
(C) 750
(D) 860
(E) 3530
A: OK... Stream of consciousness: 10^2 - 20 = 80
20^2 - 30 = 370
30^2 - 40 = 860
40^2 - 50 = 1550
50^2 - 60 = 2440
60^2 - 70 = 3530.
The answer is (E).

Q: A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 340 m long?
Options:
(A) 56 sec
(B) 42 sec
(C) 45 sec
(D) 48 sec
(E) 50 sec
A: OK... Stream of consciousness: Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 360 + 340 = 700 m
Required time = 700 * 2/25 = 56 sec
The answer is (A).

Q: How much more would Rs.20000 fetch, after two years, if it is put at 20% p.a. compound interest payable half yearly than if is put at 20% p.a. compound interest payable yearly?
Options:
(A) 482
(B) 442
(C) 552
(D) 662
(E) 526
A:
OK... Stream of consciousness: 20000(11/10)4 - 20000(6/5)2 = 482
The answer is (A).