question: 189. The inside dimensions of a rectangular wooden box
are 10 inches by 12 inches by 14 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 14x12 width x length. The biggest cylinder must fit both dimensions, so it must have at most a diameter of 12, so the radius will be 6. The answer is (D).
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question: A man can buy a new house in 4 years with all of his earnings. But he spend the same amount in household expenses in 8 years and for savings in 12 years. How many time needed for buying the house?
Options:
(A) 12
(B) 20
(C) 30
(D) 15
(E) 24
answer: Stream of consciousness: His savings in 1 year = 1/4 - (1/8+ 1/12) = 1/24
He can buy a new house in 24 years The answer is (E).
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question: There are 18 balls in a jar. You take out 3 black balls without putting them back inside, and now the probability of pulling out a black ball is 1/3. How many blue balls were there in the beginning?
Options:
(A) 12.
(B) 9.
(C) 8.
(D) 7.
(E) 6.
answer: Stream of consciousness: 8 = 3 blue balls + 15 / 3 The answer is (C).
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question: If the three-digit number 5W2 is evenly divisible by 8, which of the following could be the digit W ?
Options:
(A) 5
(B) 4
(C) 3
(D) 2
(E) 1
answer:
Stream of consciousness: Tried to locate a '0' ending multiple of 8 between 500599
Only 560 is present
560 is divisible by 8, so (560 - 8) is also divisible by 8 = 5 The answer is (A).
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