q: The average of first six prime numbers greater than 20 is?
Options:
(A) 10
(B) 20
(C) 30
(D) 40
(E) 34
a: Stream of consciousness: 23 + 29 + 31 + 37 + 41 + 43 = 204/6 = 34 The answer is (E).

question: 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) 4
(B) 7
(C) 6
(D) 8
(E) 9
answer: Stream of consciousness: S = 600/40 = 15 mps
S = 3600/15 = 240 sec = 4 min The answer is (A).

q: Which of the following numbers is divisible by each one of 3, 7, 9 and 11?
Options:
(A) 639
(B) 2079
(C) 3791
(D) 37911
(E) None of these
a: Stream of consciousness: 639 is not divisible by 7;
2079 is divisible by each one of 3, 7, 9, 11. The answer is (B).

question: In what time will a railway train 52 m long moving at the rate of 24 kmph pass a telegraph post on its way?
Options:
(A) 3 sec
(B) 4 sec
(C) 8 sec
(D) 6 sec
(E) 7 sec
answer: Stream of consciousness: T = 52/24 * 18/5 = 8 se The answer is (C).

q: There are two water tanks A and B, A is much smaller than B. While water fills at the rate of one liter every hour in A, it gets filled up like 10, 20, 40, 80, 160 in tank B. (At the end of first hour, B has 10 liters, second hour it has 20, third hour it has 40 and so on). If tank B is 1/32 filled after 21 hours, what is the total duration required to fill it completely?
Options:
(A) 22
(B) 28
(C) 269
(D) 26
(E) 82
a: Stream of consciousness: The data related to the first tank A is not necessary. As you can see, the capacity that gets filled in the tank B after each hour is doubled. So If the tank is 1/32nd part is full after 21 hours, it is 1/16th part full after 22 hours, 1/8th part full after 23 hours, 1/4th part full after 24 hours, 1/2 full after 25 hours, completely full after 26 hours. The answer is (D).

q: The average of 11 results is 48, if the average of first six results is 49 and that of the last six is 52. Find the sixth result?
Options:
(A) 21
(B) 56
(C) 78
(D) 25
(E) 23
a:
Stream of consciousness: 1 to 11 = 11 * 48 = 528
1 to 6 = 6 * 49 = 294
6 to 11 = 6 * 52 = 312
6th = 294 + 312 528 = 78 The answer is (C).