A fair coin is tossed four time. What is the probability that at most three tails occur?

Options

A. `7//9`
B. `15//16`
C. `13//16`
D. `3//4`

Answer

B

Explanation

`n(S)=2^(4)=16`
and `n(E)=.^(4)C_(0)+.^(4)C_(1)+.^(4)C_(2)+.^(4)C_(3)`
`=1+4+(4xx3)/(2xx1)+4=1+4+6+4=15`
`therefore P(E)=(n(E))/(n(S))=(15)/(16)`