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: For all integers x>1. <x>=2x+(2x-1)+(2x-2)+......2+1. What is the value of <2>*<4>?

 Option A:  60

 Option B:  116

 Option C:  210

 Option D:  263

 Option E:  360
[EX A]: Option E

[EX Q]: Question: The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 kms in 4 hours, then the speed of the first train is:

 Option A: 70 km/hr

 Option B: 75 km/hr

 Option C: 84 km/hr

 Option D: 87.5 km/hr

 Option E: 88.5 km/hr
[EX A]: Option D

[EX Q]: Question: A box contains 100 balls, numbered from 1 to 100. If three balls are selected at random and with replacement from the box, what is the probability J that the sum of the three numbers on the balls selected from the box will be odd?

 Option A: 1/4

 Option B: 3/8

 Option C: 1/2

 Option D: 5/8

 Option E: 3/4
[EX A]:
Option C