Question

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

Answer 1

When a coin is tossed twice, the sample space S is given by, S={ ( H,H ),( H,T ),( T,H ),( T,T ) }.

So, the number of elements in S is,

n( S )=4

Let, A be the event “at least one tail occurs”.

A={ ( H,T ),( T,H ),( T,T ) }

Hence, n( A )=3

Probability that when a coin is tossed twice at least one tail occurs is given by,

P( A )= number of outcomes favourable to A Total number of outcomes = n( A ) n( S ) = 3 4

Thus, the probability that when a coin is tossed twice at least one tail occurs is 3 4 .