Question

A coin is tossed twice, what is the probability that atleast one tail occurs?

Answer 1

When a coin is tossed twice, the sample space is given by
S = {HH, HT, TH, TT}
Let A be the event of the occurrence of at least one tail.
Accordingly, A = {HT, TH, TT}
$∴P(A)=\frac{\text{Number of outcomes favourable to A}}{\text{Total number of possible outcomes}}$
$=\frac{n(A)}{n(S)}$
$=\frac{3}{4}$