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.

[EX Q]: Question: A certain electric-company plan offers customers reduced rates for electricity used between 8 p.m. and 8 a.m. weekdays and 24 hours a day Saturdays and Sundays. Under this plan, the reduced rates Z apply to what fraction of a week?

 Option A:  1/2

 Option B:  5/8

 Option C:  9/14

 Option D:  16/21

 Option E:  9/10
[EX A]: Option C

[EX Q]: Question: Two trains start simultaneously from opposite ends of a 160-km route and travel toward each other on parallel tracks. Train X, traveling at a constant rate, completes the 160-km trip in 5 hours. Train Y, travelling at a constant rate, completes the 160-km trip in 3 hours. How many kilometers had Train X traveled when it met Train Y?

 Option A: 56

 Option B: 58

 Option C: 60

 Option D: 62

 Option E: 64
[EX A]: Option C

[EX Q]: Question: A man gets a simple interest of Rs.1000 on a certain principal at the rate of 5% p.a in two years. Find the compound interest the man will get on twice the principal in two years at the same rate.

 Option A: Rs.500

 Option B: Rs.250

 Option C: Rs.5012.50

 Option D: Rs.512.5

 Option E: None of these.
[EX A]:
Option D