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.
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Question: Question: A fish can go upstream at 35 kmph and downstream at 55 kmph, and then find the speed of the fish in still water?

 Option A: 45

 Option B: 55

 Option C: 35

 Option D: 65

 Option E: 70

Answer: Option A


Question: Question: Find compound interest on Rs. 5000 at 12% per annum for 1 year, compounded half-yearly.

 Option A: Rs. 600

 Option B: Rs. 618

 Option C: Rs. 525

 Option D: Rs. 620

 Option E: None

Answer: Option B


Question: Question: The ages of two friends is in the ratio of 6:5.If the sum of their ages is 66. Then after how many years will the ratio become 7:6?

 Option A: 5

 Option B: 6

 Option C: 8

 Option D: 9

 Option E: 10

Answer:
Option B