Detailed Instructions: 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: a fair 2 sided coin is flipped 7 times. what is the probability that tails will be the result at least twice, but not more than 7 times ?
Options: a. 119 / 128, b. 120 / 113, c. 114 / 210, d. 121 / 141, e. 104 / 117
Solution:
a