question: 10 books are placed at random in a shelf. The probability that a pair of books will always be together is
Options:
(A) 1/9
(B) 1/7
(C) 1/5
(D) 1/6
(E) 1/3
answer: Stream of consciousness: 10 books can be rearranged in 10! ways consider the two books taken as a pair then number of favourable ways of getting these two books together is 9! 2!
Required probability = 1/5 The answer is (C).

q: If C is the temperature in degrees Celsins and F is the temperature in degrees Fahrenheit, then the relationship between temperatures on the two scales is expressed by the equation 9C=5(F-32). In a weekly range of temperature recorded at a certain weather station differed by 25 degrees on the Fahrenheit scale, by how many degrees did the temperature extremes differ on the Celsius scale?
Options:
(A) a) 65/9
(B) b) 13
(C) c) 25
(D) d) 45
(E) e) 81
a: Stream of consciousness: The relationship is 9/5 - 32, so approximately half of difference in Celsius (the -32 part won't be used in this case). Just looking at the answer choices you can pick B which is the only number near half of 25. The other answer choices are too far apart so no need to calculate. The answer is (B).

question: Two persons A and B can complete a piece of work in 20 days and 40 days respectively. If they work together, what part of the work will be completed in 5 days?
Options:
(A) 1/8
(B) 1/3
(C) 3/6
(D) 3/8
(E) 5/3
answer: Stream of consciousness: A's one day's work = 1/20
B's one day's work = 1/40
(A + B)'s one day's work = 1/20 + 1/40 = 3/40
The part of the work completed in 5 days = 5 (3/40) = 3/8. The answer is (D).

q: A money lender lends Rs.2000 for six months at 20% p.a. rate. It the interest is reckoned quarterly than find the amount given after time limit.
Options:
(A) 2205
(B) 3387
(C) 2882
(D) 2997
(E) 1278
a: Stream of consciousness: A = 2000(21/20)2 = 2205 The answer is (A).

question: A train running at the speed of 60 km/hr crosses a pole in 12 seconds. Find the length of the train?
Options:
(A) 150
(B) 872
(C) 287
(D) 200
(E) 212
answer: Stream of consciousness: Speed = 60*(5/18) m/sec = 50/3 m/sec
Length of Train (Distance) = Speed * Time
(50/3) * 12 = 200 meter The answer is (D).

question: When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 4 times, what is the probability that it will land on the same side each time?
Options:
(A) 1/8
(B) 1/4
(C) 1/16
(D) 1/2
(E) 1/32
answer:
Stream of consciousness: Must be either 4 tails or 4 heads
1/2*1/2*1/2*1/2+1/2*1/2*1/2*1/2
1/16 + 1/16 = 1/8 The answer is (A).