question: A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that atleast one bulb is good.
Options:
(A) 6/63
(B) 2/63
(C) 125/126
(D) 1/126
(E) 1/63
answer: Stream of consciousness: Required probability = 1 - 1/126 = 125/126 The answer is (C).

q: The average of 11 results is 50, 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) 18
(D) 25
(E) 23
a: Stream of consciousness: 1 to 11 = 11 * 50 = 550
1 to 6 = 6 * 49 = 294
6 to 11 = 6 * 52 = 312
6th = 294 + 312 550 = 56 The answer is (B).

question: When N is divided by 10 the remainder is 1 and when N is divided by 3 the remainder is 2. What is the remainder Q when N is divided by 30?
Options:
(A) (a) 4
(B) (b) 7
(C) (c) 11
(D) (d) 13
(E) (e) 17
answer: Stream of consciousness: N ends in the digit 1 because when N is divided by 10, the remainder is 1. Since N ends in 1, the remainder Q when N is divided by 30 also ends in a 1. 11 is the only choice which ends in a 1. The answer is (C).

q: A train 495 m long is running at a speed of 63 km/hr. In what time will it pass a bridge 240 m long?
Options:
(A) 39
(B) 40
(C) 41
(D) 42
(E) 43
a: Stream of consciousness: Speed = 63 * 5/18 = 35/2 m/sec
Total distance covered = 495 +240 = 735 m
Required time = 700 * 2/35 = 42 sec The answer is (D).

question: Before lunch, a painter can paint a wall at a rate of r square feet per minute. The same painter, after lunch and a cup of coffee, can paint the same wall at a rate r + 1 square feet per minute, and the same wall would be finished in 30 seconds less time. What is the value of r?
Options:
(A) 1/3
(B) 3
(C) 1/2
(D) 1
(E) 2
answer: Stream of consciousness: Convert 30 seconds to 1/2 minute
Equation: 1/r = 1/(r + 1) + 1/2
Plug options into the equation:
D fits: 1/1 = 1/(1 + 1) + 1/2 The answer is (D).

question: If n is an integer, then the least possible value of |15 - 8n| is?
Options:
(A) 0
(B) 2
(C) 1
(D) 3
(E) 5
answer:
Stream of consciousness: |15 - 8n| represents the distance between 15 and 8n on the number line. Now, the distance will be minimized when 8n, which is multiple of 8, is closest to 15. Multiple of 8 which is closest to 15 is 16 (for n = 2), so the least distance is 1: |15 - 16| = 1. The answer is (C).