question: Pipe A can fill a tank in 5 hours, pipe B in 10 hours and pipe C in 30 hours. If all the pipes are open, in how many hours will the tank be filled?
Options:
(A) 2
(B) 2.2
(C) 3
(D) 3.5
(E) 4
answer: Stream of consciousness: Part filled by A + B + C in 1 hour = 1/5 + 1/10 + 1/30 = 1/3
All the three pipes together will fill the tank in 3 hours. The answer is (C).
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question: 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) 30 Years
(B) 31 Years
(C) 32 Years
(D) 34 Years
(E) 49 Years
answer: 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
There is a shortcut for these type of problems
Teacher's age is 16+(33X1) = 49 Years The answer is (E).
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question: Find a a prime number from the options below.
Options:
(A) 37
(B) 38
(C) 39
(D) 40
(E) 42
answer: Stream of consciousness: Clearly, 37 is a prime number. The answer is (A).
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question: A motorcyclist goes from Bombay to Pune, a distance of 192 kms at an average of 32 kmph speed. Another man starts from Bombay by car 2 ½ hours after the first, and reaches Pune ½ hour earlier. What is the ratio of the speed of the motorcycle and the car?
Options:
(A) 3:5
(B) 4:5
(C) 2:5
(D) 2:4
(E) 2:7
answer:

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: T = 160/32 = 5 h
T = 5 - 3 = 2
Time Ratio = 5:2
Speed Ratio = 2:5 The answer is (C).
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