Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.
--------
Question: Problem: a train of length 250 m crosses a bridge of length 150 m in 20 seconds. what is the speed of train ?
Options: a. 33, b. 27, c. 25, d. 22, e. 72

Answer: e

Question: Problem: an error 1 % in excess is made while measuring the side of a square. the percentage of error in the calculated area of the square is :
Options: a. 2.01, b. 30.1, c. 3.01, d. 25.01, e. 4.05

Answer: a

Question: Problem: let a be the event that a randomly selected two digit number is divisible by 3 and let b be the event that a randomly selected two digit number is divisible by 10. what is p ( a and b. ?
Options: a. 1 / 30, b. 1 / 15, c. 1 / 5, d. 1 / 3, e. 1 / 2

Answer:
a