q: If six persons sit in a row, then the probability that three particular persons are always together is ?
Options:
(A) 1/6
(B) 1/2
(C) 1/5
(D) 1/2
(E) 1/1
a: Stream of consciousness: Six persons can be arranged in a row in 6! ways. Treat the three persons to sit together as one unit then there four persons and they can be arranged in 4! ways. Again three persons can be arranged among them selves in 3! ways. Favourable outcomes = 3!4! Required probability = 3!4!/6! = 1/5 The answer is (C).


question: 189. The inside dimensions of a rectangular wooden box
are 8 inches by 10 inches by 12 inches. A cylindrical
canister is to be placed inside the box so that it stands
upright when the closed box rests on one of its six
faces. Of all such canisters that could be used, what is
the radius, in inches, of the one that has maximum
volume?
Options:
(A)  3
(B)  4
(C)  5
(D)  6
(E)  8
answer: Stream of consciousness: Since the radius is squared, the biggest volume cylinder will have the biggest possible radius. To achieve that, let the smaller dimension of the rectangular box be the height. So, it will have 12x10 width x length. The biggest cylinder must fit both dimensions, so it must have at most a diameter of 10, so the radius will be 5. The answer is (C).


q: Three 6 faced dice are thrown together. The probability that exactly two dice show the same number on them is -.
Options:
(A) 5/12
(B) 4/13
(C) 5/17
(D) 3/12
(E) 8/9
a: Stream of consciousness: Using question number 11 and 12, we get the probability as
1 - (1/36 + 5/9) = 5/12 The answer is (A).


question: A die is thrown. If G is the event 'the number appearing is a multiple of 3' and H be the event
'the number appearing is even' then find whether G and H are independent ?
Options:
(A) G and H are not independent events.
(B) G and H are independent events.
(C) Only G independent event
(D) Only H independent event
(E) None
answer: Stream of consciousness: We know that the sample space is S = {1, 2, 3, 4, 5, 6}
Now G = { 3, 6}, F = { 2, 4, 6} and E n F = {6}
Then P(G) = 2/6 = 1/3
P(H) = 3/6 = 1/2 and P(G ∩ H) = 1/6
P(G n H) = P(G). P (H)
G and H are independent events. The answer is (B).


q: A man rows his boat 84 km downstream and 48 km upstream, taking 2 hours each time. Find the speed of the stream?
Options:
(A) 6 kmph
(B) 5 kmph
(C) 9 kmph
(D) 8 kmph
(E) 1 kmph
a: Stream of consciousness: Speed downstream = d/t = 84/(2) = 42 kmph
Speed upstream = d/t = 48/(2) = 24 kmph
The speed of the stream = (42 - 24)/2 = 9 kmph The answer is (C).


q: The average age of a class of 32 students is 16 yrs. if the teacher's age is also included, the average increases by one year. Find the age of the teacher
Options:
(A) 49
(B) 88
(C) 25
(D) 18
(E) 11
a:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Stream of consciousness: Total age of students is 32X16 = 512 Years
Total age inclusive of teacher = 33X (16+1) = 561
So, Teacher's age is 561-512 = 49 Yrs The answer is (A).