question: A box contains 3 blue marbles, 4 red, 6 green marbles and 2 yellow marbles. If four marbles are picked at random, what is the probability that none is blue?
Options:
(A) 17/91
(B) 33/91
(C) 51/91
(D) 65/91
(E) None of these
answer: Stream of consciousness: Given that there are three blue marbles, four red marbles, six green marbles and two yellow marbles. When four marbles are picked at random, then the probability that none is blue is = C/C = (12 * 11 * 10 * 9)/(15 * 14 * 13 * 12) = 33/91 The answer is (B).

q: What is the are of an equilateral triangle of side 16 cm?
Options:
(A) 646
(B) 649
(C) 644
(D) 643
(E) 642
a: Stream of consciousness: Area of an equilateral triangle = 3/4 S2
If S = 16, Area of triangle = 3/4 * 16 * 16 = 643 cm2; The answer is (D).

question: Marry has 3 trousers in cupboard. One of them is grey the 2nd blue and the 3rd brown. In his wardrobe he also has 4 shirts. One of them is grey and the other 3are white. He opens his cupboardin the dark and pick out one shirt trouser pair without examination the color. What is the likelihood that neither the shirt nor the trouser is grey?
Options:
(A) 1/2
(B) 2/3
(C) 3/5
(D) 5/7
(E) 5/8
answer: Stream of consciousness: Probability that trouser is not grey = 2/3
Probability that shirt is not grey = 3/4
Required probability = 2/3 x 3/4 = 1/2 The answer is (A).

q: In a race with 30 runners where 6 trophies will be given to the top 6 runners (the trophies are distinct: first place, second place, etc), how many ways can this be done?
Options:
(A) 6^6 ways
(B) 8^9 ways
(C) 7^8 ways
(D) 8^7 ways
(E) 8^6 ways
a: Stream of consciousness: 6 people can be prized with distinct prizes in 6^6 ways The answer is (A).

question: The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?
Options:
(A) 22
(B) 28
(C) 29
(D) 20
(E) 21
answer: Stream of consciousness: Average of 20 numbers = 0
Sum of 20 numbers = (0 * 20) = 0
It is quite possible that 19 of these numbers may be positive and if their sum is a, then 20th number is (-a). The answer is (D).

question: A can do a piece of work in 12 days. When he had worked for 2 days B joins him. If the complete work was finished in 8 days. In how many days B alone can finish the work?
Options:
(A) 18 days
(B) 11 days
(C) 77 days
(D) 188 days
(E) 66 days
answer:
Stream of consciousness: 8/12 + 6/x = 1
X = 18 days The answer is (A).