An unbiased coin is tossed eight times. The probability of obtaining at least one head and at least one tail is: (1) $\frac { 127 } { 128 }$ (2) $\frac { 63 } { 64 }$ (3) $\frac { 255 } { 256 }$ (4) $\frac { 1 } { 2 }$
An unbiased coin is tossed eight times. The probability of obtaining at least one head and at least one tail is:\\
(1) $\frac { 127 } { 128 }$\\
(2) $\frac { 63 } { 64 }$\\
(3) $\frac { 255 } { 256 }$\\
(4) $\frac { 1 } { 2 }$