instruction:
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.
question:
Question: Two pipes A and B can fill a cistern in 20 and 30 minutes respectively, and a third pipe C can empty it in 40 minutes. How long will it take to fill the cistern if all the three are opened at the same time?

 Option A: 17 1/5

 Option B: 17 1/8

 Option C: 17 1/7

 Option D: 17 1/1

 Option E: 17 1/2
answer:
Option C


question:
Question: Car X began traveling at an average speed of 35 miles per hour. After 72 minutes, car Y began traveling at an average speed of 41 miles per hour. When both cars had traveled the same distance, both cars stopped. How many miles did car X travel from the time car Y began traveling until both cars stopped?

 Option A: 140

 Option B: 175

 Option C: 210

 Option D: 245

 Option E: 280
answer:
Option D


question:
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
answer:

Option C