q: A train 90 meters long completely crosses a 200 meters long bridge in 36 seconds. What is the speed of the train is?
Options:
(A) 29
(B) 40
(C) 25
(D) 66
(E) 09
a: Stream of consciousness: S = (90 + 200)/36 = 290/36 * 18/5 = 29 The answer is (A).

question: A pipe can fill a cistern in 20 minutes whereas the cistern when fill can be emptied by a leak in 30 minutes. When both pipes are opened, find when the cistern will be full?
Options:
(A) 17 minutes
(B) 87 minutes
(C) 60 minutes
(D) 27 minutes
(E) 11 minutes
answer: Stream of consciousness: 1/20 - 1/30 = 1/60
60 minutes The answer is (C).

q: An analyst will recommend a combination of 3 industrial stocks, 2 transportation stocks, and 2 utility stocks. If the analyst can choose from 5 industrial stocks, 3 transportation stocks, and 4 utility stocks, how many different combinations of 7 stocks are possible?
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Options:
(A) 180
(B) 19
(C) 60
(D) 12
(E) 720
a: Stream of consciousness: 5C3 * 4C2 * 3C2 = 10*6*3 = 180. The answer is (A).

question: The average of nine numbers is 17. The average of first four numbers is 20 and the average of last four numbers is 16. What is the middle number?
Options:
(A) A) 7
(B) B) 8
(C) C) 9
(D) D) 10
(E) E) 11
answer: Stream of consciousness: The total of nine numbers = 9X17 = 153
The total of first 4 and last 4 numbers is = 4 X 20+4 X 16 = 144
So, the middle number is (153 - 144 ) = 9 The answer is (C).

q: The edge of a cube is 9a cm. Find its surface?
Options:
(A) 153a2 cm2
(B) 143a2 cm2
(C) 233a2 cm2
(D) 243a2 cm2
(E) 253a2 cm2
a: Stream of consciousness: 6a2 = 6 * 9a * 9a = 243a2 The answer is (D).

q: A teacher has to choose the maximum different groups of three students from a total of six students. Of these groups, in how many groups there will be included in a particular student?
Options:
(A) 6
(B) 8
(C) 10
(D) 12
(E) 15
a:
Stream of consciousness: If students are A, B, C, D, E and F; we can have 6C3 groups in all. However, if we have to count groups in which a particular student (say A) is always selected we would get 5C2 = 10 ways of doing it. The answer is (C).