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: Rahim bought 4 pillows with the average cost of $5. If Rahim also buys the fifth pillow with the price of $ 10, what is the average (arithmetic mean) price of those 5 pillows?

 Option A: $6

 Option B: $5

 Option C: $5.5

 Option D: $6.5

 Option E: $7
Option A

Question: How much more would Rs.20000 fetch, after two years, if it is put at 20% p.a. compound interest payable half yearly than if is put at 20% p.a. compound interest payable yearly?

 Option A: 482

 Option B: 297

 Option C: 278

 Option D: 298

 Option E: 279
Option A

Question: A 300 meter long train crosses a plaƞorm in 39 seconds while it crosses a signal pole in 18 seconds.
What is the length of the plaƞorm.

 Option A: 310 meter

 Option B: 335 meter

 Option C: 345 meter

 Option D: 350 meter

 Option E: None of these

Option D