A coin is tossed 6 times . Find the probability of getting at least 3 heads .

Answer

`(21)/(32)`

Explanation

In a single toss `P(H ) =(1)/(2) " and (not H) " =(1)/(2)`
`:. , p =(1)/(2) , q =(1)/(2) " and " n=6`
Let X show the number of heads . Then
`P(X =r)=.^(n)C_(r ).p^(r ) .q^((n-r)) =.^(6)C_(r ).((1)/(2))^(6)`
Required probability `=P(X =3) +P(X =4) +P(X =5) +P(X=6)`