A fiar coin is tossed 18 times. Find the probability that it shows least once.

Explanation

p = come in head on a fair coin
`p=(1)/(2), q=1 -(1)/(2)=(1)/(2)`
If head don't come any time
`=.^(8)C_(0)q^(0)q^(8)`
`=.^(8)C_(0)((1)/(2))^(0)((1)/(2))^(8)`
`=1xx(1)/(2^(8))=(1)/(256)`
`therefore ` Shows heads atlest once `=1-(1)/(256)=(255)/(256)`