q: A telephone company needs to create a set of 3-digit area codes. The company is entitled to use only digits 2, 4 and 5, which can be repeated. If the product of the digits in the area code must be odd, how many different codes can be created?
Options:
(A) 20
(B) 22
(C) 24
(D) 1
(E) 30
a: Stream of consciousness: Total # of codes possible is 3*3*3 = 27. Oit of those 27 codes only the product of 555 will be odd, the remaining 26 will have either 2 or 4 in them, which ensures that their product will be even. Therefore the number of codes where the product of the digits is even = (total) - (restriction) = 27 - 26 = 1. The answer is (D).

question: How many factors does 34^2 have?
Options:
(A) 2
(B) 8
(C) 20
(D) 25
(E) 26
answer: Stream of consciousness: 36^2 = 6*6*6*6 = 2^4*3^4
Total factors = (4+1)*(4+1) = 5*4 = 20 The answer is (C).

q: 100 white and black tiles will be used to form a 20x20 square pattern. If there must be at least one black tile in every row and at least one white tile in every column, what is the maximum difference between the number of black and white tiles that can be used?
Options:
(A) 75
(B) 70
(C) 85
(D) 90
(E) 95
a: Stream of consciousness: Answer = B
Please refer diagram below
90 - 20 = 70 The answer is (B).

question: A can do a piece of work in 4 hours; B and C together can do it in 2 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?
Options:
(A) 2hours
(B) 3hours
(C) 4hours
(D) 5hours
(E) 6hours
answer: Stream of consciousness: A's 1 hour work = 1/4;
(B + C)'s 1 hour work = 1/2;
(A + C)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/4 + 1/2) = 3/4
B's 1 hour work = (3/4 - 1/2) = 1/4
B alone will take 4 hours to do the work. The answer is (C).

q: How much is 55% of 40 is greater than 4/5 of 25?
Options:
(A) 29
(B) 776
(C) 2
(D) 12
(E) 99
a: Stream of consciousness: (55/100) * 40 (4/5) * 25
22 - 20 = 2 The answer is (C).

q: A 160 meter long train crosses a man standing on the platform in 16 sec. What is the speed of the train?
Options:
(A) 36 kmph
(B) 54 kmph
(C) 92 kmph
(D) 86 kmph
(E) 76 kmph
a:
Stream of consciousness: S = 160/16 * 18/5 = 36 kmph The answer is (A).