question: A, B and C can do a work in 7 days, 8 days and 12 days respectively. In how many days can all three of them working together, complete the work?
Options:
(A) 2 50/59
(B) 2 5/59
(C) 2 2/50
(D) 2 2/59
(E) 2 1/59
answer: Stream of consciousness: Work done by all three of them in one day = 1/7 + 1/8 + 1/12 = 59/168
The number of days required = 168/59 = 2 50/59 days. The answer is (A).

q: All of the bonds on a certain exchange are designated by a 3-letter, a 4-letter, or a 5-letter code that is created by using the 26 letters of the alphabet. Which of the following gives the maximum number of different bonds that can be designate with these codes?
Options:
(A) 26(26^3 + 26^4)
(B) 26(26^3 + 26^5)
(C) 27(26^3 + 26^5)
(D) 27(26^3) + 26^5
(E) 26^3 + 27(26^5)
a: Stream of consciousness: 3-letter codes = 26^3;
4-letter codes = 26^4;
5-letter codes = 26^5;
Total = 26^3 + 26^4 + 26^5 = 26^3(1+26) + 26^5 = 26^3*27 + 26^5. The answer is (D).

question: Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?
Options:
(A) 820 gallons
(B) 128 gallons
(C) 120 gallons
(D) 129 gallons
(E) 220 gallons
answer: Stream of consciousness: Work done by the waste pipe in 1 minute = 1/15 - (1/20 + 1/24) = - 1/40
Volume of 1/40 part = 3 gallonsVolume of whole = 3 * 40 = 120 gallons. The answer is (C).

q: In 1 kg mixture of sand and iron, 20% is iron. How much sand should be added so that the proportion of iron becomes 10%?
Options:
(A) 1 kg
(B) 200 gms
(C) 800 gms
(D) 1.8 kg
(E) None of these
a: Stream of consciousness: In 1 kg mixture quantity of iron = 200 gm
Let x gm sand should be added, then
10% of (1000 + x) = 200
\ x = 1000 gm = 1 kg The answer is (A).

question: Solve:-
333 x 333 x 333 + 555 x 555 x 555 = ?(333 x 333 - 333 x 555 + 555 x 555)
Options:
(A) 888
(B) 333
(C) 555
(D) 988
(E) 889
answer: Stream of consciousness: Given Exp. = (a3 + b3) = (a + b) = (333 + 555) = 888(a2 - ab + b2) The answer is (A).

question: Find the probability that the number drawn is a factor of 50.
Options:
(A) 1/25
(B) 1/50
(C) 3/25
(D) 3/50
(E) 7/50
answer:
Stream of consciousness: The factors of 50 are 1, 2, 5, 10, 25, 50
Therefore, required probability = 6/100 = 3/50. The answer is (D).