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 a certain coin is flipped, the probability that the coin will land heads is 1 / 2. if the coin is flipped 6 times, what is the probability that it will land heads up on the first 4 flips but not on the last 2 flips ?
Options: a. 1 / 8, b. 1 / 16, c. 1 / 32, d. 1 / 64, e. 1 / 128

SOLUTION: d

PROBLEM: Problem: a fraudulent dairy guy declares to market his dairy at price range but he combined it with water and therefore benefits 25 %. the percentage of water in the combination is :
Options: a. 20 %, b. 30 %, c. 50 %, d. 35 %, e. 60 %

SOLUTION: a

PROBLEM: Problem: when positive integer n is divided by 3, the remainder is 1. when n is divided by 7, the remainder is 5. what is the smallest positive integer k such that k + n is a multiple of 21 ?
Options: a. 2, b. 4, c. 6, d. 8, e. 10

SOLUTION:
a