You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Q: Question: In what time will a train 200 m long cross an electric pole, it its speed be 144 km/hr?

 Option A: 2.5 sec

 Option B: 2.9 sec

 Option C: 3.5 sec

 Option D: 7.5 sec

 Option E: 5 sec

A: Option E
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Q: Question: A is twice as fast as B. If B alone can do a piece of work in 18 days, in what time can A and B together complete the work?

 Option A: 10

 Option B: 16

 Option C: 18

 Option D: 6

 Option E: 12

A: Option D
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Q: Question: The third proportional to 1 and 2 is?

 Option A: 8

 Option B: 7

 Option C: 4

 Option D: 5

 Option E: 3

A:
Option C
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