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 shopkeeper sold an book offering a discount of 5% and earned a profit of 30%. What would have been the percentage of profit earned if no discount was offered?

 Option A: 140

 Option B: 120

 Option C: 130

 Option D: 136.8

 Option E: 150
[EX A]: Option D

[EX Q]: Question: The average age of 15 students of a class is 15 years. Out of these, the average age of 4 students is 14 years and that of the other 10 students is 16 years, The age of the 15th student is

 Option A: 11

 Option B: 12

 Option C: 9

 Option D: 14

 Option E: 15
[EX A]: Option C

[EX Q]: Question: A train crosses a platform of 100 m in 15 sec, same train crosses another platform of length 250 m in 20 sec. then find the length of the train?

 Option A: 150

 Option B: 88

 Option C: 77

 Option D: 62

 Option E: 350
[EX A]:
Option E