If two unbiased coins are tossed simultaneously, then the total outcomes may be HH,HT,TH,TT.
No. of total outcomes = 4
(i) two heads
favourable outcome for two heads are HH.
No. of favourable outcomes = 1
P(two heads)=14
(ii) favourable outcome for one tail are TH,HT.
No. of favourable outcomes = 2
P(one tail)=24=12
(iii) favourable outcome for at least one tail are are TH,HT,TT.
No. of favourable outcomes = 3
P(at least one tail)=34
(iv) favourable outcome for at least one head are are TH,HT,HH.
No. of favourable outcomes = 3
P(at least one head)=34
(v) favourable outcome for no tail are HH.
No. of favourable outcomes = 1
P(no tail)=14