TASK DEFINITION: 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.
PROBLEM: Problem: if 20 typists can type 50 letters in 30 minutes, then how many letters will 40 typists working at the same rate complete in 1 hour ?
Options: a. 400, b. 500, c. 350, d. 250, e. 200

SOLUTION: a

PROBLEM: Problem: the ` ` racing magic ' ' takes 120 seconds to circle the racing track once. the ` ` charging bull ' ' makes 40 rounds of the track in an hour. if they left the starting point together, how many minutes will it take for them to meet at the starting point for the second time ?
Options: a. 3, b. 6, c. 9, d. 12, e. 15

SOLUTION: d

PROBLEM: Problem: a vessel of capacity 60 litres is fully filled with pure milk. nine litres of milk is removed from the vessel and replaced with water. nine litres of the solution thus formed is removed and replaced with water. find the quantity of pure milk in the final milk solution ?
Options: a. 23.89, b. 72.9, c. 38.3, d. 43.35, e. 79.3

SOLUTION:
d