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 bus takes 3 hours to cover a distance of 500 Km. how much should the speed in Kmph be maintained to cover the same direction in 5/3th of the previous time?

 Option A: 75 Kmph

 Option B: 100 Kmph

 Option C: 90 Kmph

 Option D: 65 Kmph

 Option E: 70 Kmph
[EX A]: Option B

[EX Q]: Question: Two pipes P and Q can fill a cistern in 12 and 14 minutes respectively. Both are opened together, but at the end of 3 minutes the first is turned off. How much longer will the cistern take to fill?

 Option A: 11 1/2 min

 Option B: 11 1/4 min

 Option C: 11 2/4 min

 Option D: 11 1/5 min

 Option E: 10 1/2 min
[EX A]: Option E

[EX Q]: Question: In a guess game , five friends had to guess the exact numbers of balls in a box.
Friends guessed as 31 , 35, 39 , 49 , 37, but none of guess was right.The guesses were off by 1, 9, 5, 3, and 9 (in a random order).
Can you determine the number of balls in a box ?

 Option A: 30 balls

 Option B: 35 balls

 Option C: 40 balls

 Option D: 45 balls

 Option E: 50 balls
[EX A]:
Option C