question: Find the invalid no.from the following series 13, 18, 25, 30, 37, 40
Options:
(A) 13
(B) 18
(C) 40
(D) 30
(E) 37
answer: Stream of consciousness: The differences between two successive terms from the beginning are 7, 5, 7, 5, 7, 5. So, 40 is wrong. The answer is (C).
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question: In how many ways can you seat 6 people on a bench if one of them, Rohit, does not want to sit on the middle seat or at either end?
Options:
(A) 360
(B) 1720
(C) 2880
(D) 5040
(E) 10080
answer: Stream of consciousness: Since Rohit does not want to sit on the middle seat or at either end (3 chairs), then he can choose 3 chairs to sit. The remaining 5 people can sit in 5! ways. Thus the # of arrangements is 3*5! = 360. The answer is (A).
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question: If P(A) = 2/15, P(B) = 4/15, and P(A B) = 6/15 Find P(A|B)
Options:
(A) 1/2
(B) 2/3
(C) 3/2
(D) 4/5
(E) 4/7
answer: Stream of consciousness: P(A|B) = P(A B)/P(B)
P(A|B) = (6/15)/(4/15) = 3/2. The answer is (C).
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question: The average of first 12 even numbers is?
Options:
(A) 19
(B) 18
(C) 16
(D) 13
(E) 17
answer:
Stream of consciousness: Sum of 12 even numbers = 12 * 13 = 156
Average = 156/12 = 13 The answer is (D).
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