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: The amount of an investment will double in approximately 70/ p years, where p is the percent interest, compounded annually. If Thelma invests $ 60,000 in a long-term CD that pays 5 percent interest, compounded annually, what will be the approximate total value of the investment when Thelma is ready to retire 42 years later?

 Option A: $ 280,000

 Option B: $ 320,000

 Option C: $ 360,000

 Option D: $ 480,000

 Option E: $ 540,000
[EX A]: Option D

[EX Q]: Question: Two pipes A&B can fill a tank in 24 min and 32 min respectively. If both the pipes are opened simultaneously, after how much time B should be closed so that the tank is full in 18 min.

 Option A: 8 min

 Option B: 3 min

 Option C: 21 min

 Option D: 23 min

 Option E: 24 min
[EX A]: Option A

[EX Q]: Question: How long does a train 100 m long traveling at 60 kmph takes to cross another train of 170 m in length has a speed of 40 kmph?

 Option A: 1.42 sec

 Option B: 16.8 sec

 Option C: 5 sec

 Option D: 1.68 sec

 Option E: 3.6 sec
[EX A]:
Option E