Q: In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
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
A:
a