As 7 coins are tossed simultaneously the total number of outcomes are \(2^7=128.\)
The favourable number of outcomes that a tail appears an odd number of times will be, \(7_{C_1}+7_{C_3}+7_{C_5}+7_{C_7}=64.\)
Thus, the probability
\(=\frac{The\,favourable\,outcomes}{The\,total\,number\,of\,outcomes}\)
\(=\frac{64}{128}\)
\(=\frac{1}{2}\)
Hence, the probability is 1/2 .
